Glad to offer some advice. I'm by no means an expert, so I'm sure you'll get some disagreement with me, but here goes...
What trade goods should I be valuing the most? Is it better to load up on a few higher value goods, or is it better to try to have a little bit of everything? Also, who should I be trading with? Should I select distant partners that I'm less likely to expand into for an extended period of time, or should I select closer partners that I might want to ally? Do you get any sort of relations buff as a trade partner, and is there a penalty for going to war with a trade partner?
Ok so the key thing to remember is that valuable trade goods are nice, but if you're big (or planning on growing) capitol trade bonuses are going to be better. So, you really,
really want 2 goods of as many types of goods in your provinces at once. There's a lot of options, but a few things to remember are:
- Stone. Always get stone. Never not have stone. Since build cost reductions are additive, they can really, well, add up.
- Cloth and papyrus. These goods boost tech rate. That's incredibly important (assuming you aren't a tribe and getting no tech whatsoever).
- Military goods. You probably want some heavy infantry in your legions. That means iron, so you might as well get the surplus in your capitol region
- Choose other bonuses based on utility. A tribe wants +tribal happiness/productivity, but if you're one of the Diadochi you probably don't care at all. The more expansionist you are, the higher AE will always be, so you want as many happiness boosts when stability gets low.
Generally, it's perfectly fine to go to war with a trade partner, but do realize this potentially means resetting a lot of your trades the moment a war begins. I don't think there's a relations boost... but I'm not sure, either. On a similar note, choose trade partners based to some degree on stability. Frankly, losing out on .2 ducats per month might be worth trading internally, just to make sure you never lose that all-important capitol bonus.
As for other provinces... me, I just set them on autotrade and forget them. Not optimal, perhaps, but honestly I can't be bothered.
What buildings are typically the best, and in what cases should I build the more situational ones? Should I try to grow settlements or focus most growth into cities?
I am still working on getting a sense of this myself, but generally the "you can only make 1 of these" buildings are the best you can get. Foundries give a major boost to production, and theaters / temples are
absolutely crucial in conversion/assimilation and keeping provinces reasonably loyal in the process. I often lag on settlement building, focusing on those big city buildings. I'd really like to hear what other people think about build order.
I am seeing ways to increase manpower through buildings, but I am not seeing buildings that give access to different units or increase the number of levies. I am sort of assuming that as manpower increases, the number of levies will also. Are the units tied to resources? Do I just have to get to the point that I can build legions if I want more control over how the army is made up?
All right, let's do a quick rundown of how I:R's military works, because it's somewhat complex and (more importantly) very different from EUIV/CK:
- Levies come from pops. You do not, repeat, do not, control their composition or size directly. They are instead calculated based on the number of pops of integrated culturein that region. Their unit composition is based on what cultures make up said integrated pops - lots of Romans will give you a decent proportion of heavy infantry, say, while lots of Scythians will net you some horse archers in the mix.
- As a result of this system, you may need to integrate some cultures to keep your military's size up. Alternatively, you can sit around and wait for them to assimilate.
- Note that while raised, you lose out on those pops' production, so keeping levies permanently raised is extremely costly. Additionally, taking heavy casualties on levies can cause associated pops to die. Legions (below) are the solution to this... or just don't lost troops in battle, because that will definitely prove practical at all times...
- All regions, even if you have a single territory with 1 pop in it, will provide a 4-unit levy as baseline (i.e. 2k troops). Unless you're small they probably won't be how you win wars, though they might be needed reinforcements or useful to take undefended province capitals.
- Manpower is needed to replenish your levies and your legions, so it's still quite important.
- Legions can be raised from your home region or from all regions, depending on your laws. They cost upkeep, but don't run the risk of killing pops, don't take away pop production, and their commanders aren't also governors (so it's much easier to assign the best characters available specifically for fighting). Importantly, each unit of troops raised in the legion is one less you get of that region's levies, so the pop-based troop budget is still a major factor.
How much control do I have over who gets elected consul, and how much of a difference does it actually make who wins?
You can improve the preferred party's popularity via offices (top left one, as I recall - the person put there boosts their party). Beyond that, you can smear someone's popularity to reduce their likability for election. Do watch out, though - you can drop them to 0 and they still get elected, which is a hassle.