Thanks for the reply.
What would you recommend for learning all the rules and gameplay mechanics. Is the faqs thread the best place?
Playing along is the best teacher I guess

... and when you come to something you can't figure out on your own, check the threads or ask.
Once you get into the game, it is not really that complicated, and most of the inconsistencies with tool-tips etc. are minor in game-play terms. When you have the basics, the rest will come smoothly.
The help threads in the FAQ section are a good reference, but much of it might not make much sense until you actually are in a situation where you need that information.
A few pointers that might not be specifically stated anywhere:
- Loyalty modifiers. Each character have a loaylty score towards their liege. This goes up or down on a monthly basis depending on a loyalty modifier. To see the loyalty of a vassal/courtier, you can go to that character's screen and see the loyalty %. If you hover over the value, you will get a break-down of what is modifying it (like traits, reputation, diplomatic skills, family, laws etc).
- Neighbouring tech. As you only reseach tech in your capital province, you sometimes might want to see what tech is available in other provinces. In the tech screen, if you select a tech, the map will show in color codes, what level each province has in that tech. So if all your other provinces have tech 2 in Siege Equipment, but your Capital only has level 1, then you might want to research something else, as it will probably spread pretty soon from one of the other provinces.
- Inheritance laws. When you plan to expand through marriages, you will need to know what inheritance laws, your target has. This works the same as tech. Select the inheritance law you want to check for, and any realm with that law will turn green. For this strategy you will need to look for semi-salic inheritance laws in realms where the ruler have only daughters.
- Travelling by sea. The calculation of the cost of travelling over ocean is done from the beginning of the journey to the end, no matter if half the trip was made over land. F.x. If you have an army in Denmark, and select it and click on Alexandria, the price will be calculated on the number of provinces you cross from Denmark to Alexandria. Instead you will want to walk the army to the italian shores, and once they arrive, you can start a new journey that only covers sea provinces ... much much cheaper.
- Vassal regiments. These are free of charge

... so use them extensively in wars. Be aware that if you raise the army through the province screen, your vassal will lose loyalty. If you request him to muster for you, he will not, but he might refuse. You can only request regiments from vassals with at least 50% loyalty. Also when you ask for their troops, they will lose loyalty if you do not have at least half your own troops mobilized (only exception is when using Grand mobilization, i suspect).
- Vassals' vassals' troops. Since characters only have loyalty towards their immediate liege, not their liege's liege, you can raise these troops from the province screen without ill effect towards you (the owner of the troops will get a loyalty drop towards his liege though).
- Own regiments and upkeep. If you have your own troops mobilized you will soon be in the poor house

... but if you are planning to keep them in your own realm, in provinces with roads built, and where they do not exceed the supply limit, you can set upkeep to 0 with no attrition. Just remember to increase upkeep when you need them anywhere else, or they will disappear fast (many have made that mistake).
- Rebels in vassal realms. The Ai doesn't seem to think these to be an issue, and rarely muster their troops to take them down, so you will have to help them out ... either with your own troops or the vassal's troops.