How does the mathematics work on the Find secrets task the spymaster can do?
Is it a flat chance to find someone's secret and then it randomly chooses one of the people at that court who has a secret and the player gets that persons secret.
Or is the chance to Find someone's secret directly related to the number of people which have secrets within that court.
Basically what I would like to know is if its more likely a spymaster can find out my secret if I am in a court where I am the only one with a secret compared to a court where I am only of many people with a secret

While I can't go into exact maths, a spymaster is, I believe, more likely to find your secret if you're the only one in court
with a secret, yes. Relative intrigue matters, and smaller secrets are easier to find than larger ones. If you're especially worried, you can always surrounded yourself with questionable individuals and let their mess of secrets and lies disguise your own indiscretions.
Thank you for the clarification, much appreciated! I will echo the curiosity of some others, though, if you're able to go into this much detail: aside from the question of who they answer to, do individual bishops still exist in the same manner as barons and mayors? Let's say, in the case that you are a single-county ruler and have a county with two or three temples in it, do they have separate holders to answer to a common archbishop, or all share the same holder? That's one point I'm still somewhat unclear on.
Not quite, I'm afraid. Your bishop controls all the temple baronies in your domain, and receives taxes from the bishops of any vassals you have that share your religion. So a count, a duke, and a king all have bishops, the duke would just receive taxes from the count's bishop, and the king from the duke's (assuming they're all vassalised sensibly to each other). In your example, the single-county ruler would have one bishop who was leasing all three temple holdings from them (making them, worryingly, up to three times as powerful as the lord in question), but who also paid some of the taxes from those holding to the bishop of the count's liege.
Nice changes, i just have few questions.
1. Is title bishop/archbishop different if you are different tier of nobility (eg. counts have bishop, dukes have archbishops on council)
2. Is there difference in power betwern bishop and archbishop rank?
3. Can you assign bishop to a job like other councilors or must he like you?
4. Can we appoint bishop as a councilor or is he appointed by pope when older one dies? Can pope replace bishops if they become to loyal to secular liege?
1) Yes! Exactly that, m'friend.
2) Technically? Nope. In practice?
Like you wouldn't believe. Levies and taxes add up, and a powerful king with a lot of land will likely have a very powerful archbishop, even though that bishop is, notionally, a humble spiritual adviser.
3) You can still assign them to different tasks, even if they're being obstinate about paying taxes.
4)

Afraid both parts of this question are classified. You'll have to wait for the religion dev diary.
One of the most disappointing things in CK2 is how the friends/rivals system is almost always wasted, because being friends or rivals with anyone other than a powerful vassal is fairly meaningless overall, and because everyone is a potential friend/rival it feels like 90% of the time you've got meaningless barons or cousins as friends/rivals where neither the benefits nor the drawbacks matter much at all to you.
Snipped your quote slightly; this is something we've put a lot of time and effort into making better! Friends and rivals should always be impactful, and we're trying to involve these relationships much more heavily in CK3.
<snipped> thirdly, an actual question: will spouses also get events and interactions based on the attribute/area of focus they’ve been empowered to help with? Things like people complaining about meddling, the spouse having a mind of their own (maybe different from yours), and just ordinary type events that your councilors might get while helping you govern?
Not something we have a huge amount of at the moment I'm afraid, but that's purely a prioritisation issue. Definitely something that we're very keen on having more and more content for in the future!
No wonder that Marshall has only a measly 6 skill, he is gripping his sword by the blade, the fool!
Shhhhh, don't tell him, he's got his best concentrating-face on. Powerful vassals, mate. They think they're all that, but they're not always as competent as they'd have you believe.
I like that there is more incentive now to have good relations with the church, but I'm not a fan of how all of this hinges on a single character. I get the impression that all you need to do now is bribe or placate single a person in your realm to have all of the church's resources at your disposal. It feels way too simplistic. Well, unless you also have church vassals who are powerful landholders on their own right, but that only very rarely happens. <snip>
Well, yes and no. A greedy bishop with similar traits to you isn't a huge obstacle, typically. You get along well with the Church, the Church gets along well with you. On the other hand, say that bishop isn't greedy. Bribes aren't so good then. Say you have a few opposing characters traits (especially if some of those are sins for your religion), now you've actually got a bit of trouble on your hands. Say this happens mid-war or just after a succession, rather than when everything is at peace. You need that sway scheme to get agents for your murder plot, but now you're having to suck up to the Church just to get your economy under control, and then the Pope drops an excommunication in your lap because you keep openly attempting to murder people, and...

Generally, I feel gameplay elements work best when they play into cascading failure. No one system should require you to focus entirely on that system to keep it working. Things should, generally, be fixable, it's just a case of where you allocate your time & resources, and if this or that problem is a priority for you right now. Even if pleasing your bishop jumps your personal priority queue most of the time, it's still causing interesting problems elsewhere just by existing.
<snip> man..... i mean, i get that its intentional that an incompetant buffoon would still demand to be given a position, and thats fine. managing that should be part of your gameplay experience and its interesting enough, and reflects reality probably. kinda always hated how everyone would almost invariably turn out completely worthless though, which immediately transforms this mechanic into one of the most irritating parts of the game for me
you couldnt intentionally groom the heir of a powerful vassal into a great marshal, for instance, unless you somehow managed to get him into your court before the ai could slam him into a learning education for no reason. the ai being smarter about this would be all well and good but like also generally allowing the player some degree of control is overall just a less frustrating experience. it should be an honor for the king to personally school your son and heir, right? what duke wouldnt want to boast hed been schoolchums with the crown prince? unless your vassal hates your guts, of course, then hed hardly want his son held hostage (but maybe you could still arrange for something like that as a punishment or in exchange for some concessions, so your vassal will think twice before getting uppity) <snip>
Ah, I'm afraid YMMV on that one, though we do still support swapping council positions without firing people, so you'd need every councillor to be utterly useless at all stats to get completely screwed over.
Oh, it is an honour. It's also a form of centralisation, power-curbing, and hostage taking that conveniently
doubles as an honour.

As a ruler, I fully support this benign charity I extend to my subjects.

As a vassal, I totally oppose this indoctrination and hostage-taking of my dynasty's greatest treasures. Even if you like the king, giving your kids to the royal court does rule out a lot of extreme options in the feudal toolkit which, for most of our timeframe, are still pretty important. Especially in the earlier start dates, the king should just be the first amongst equals, and has no right to raise your kids if you don't expressly want them to.
Wait, I'm confused about the bishop. He doesn't *own* the temple holdings, right? I expect the holdings may have different baron-tier priests which in turn have different lieges, and all the priests send their monies and levies to your bishop. Is that correct?
Not
quite.

Bishops use a mechanic called leasing: if I'm a one-county count, and my single county has a single temple holding, I automatically lease that holding to my bishop. I still own it, it's always considered an inalienable part of my counties, but the taxes and levies go straight to the bishop. In other words, rather than have a dozen minor bishops per sizeable sub-realm all sending taxes to your bishop, your bishop simply receives all the income directly. If I then had a liege with a bishop of the same religion, my bishop would also pay a portion of this income on to my liege's bishop.