Economic tips for non naval nations anyone? Maximizing profit?

Ok I have played as britain for about 30 turns and found it too easy due to the fact that having naval dominance and trade makes the economy very large and wealthy. It's a little too easy for my liking. So i decided to play as nations like prussia, Russia, and Austria. Now I just about industrialized everything and have a very large economy that doesn't rely on naval trade too much. I have 2 indiamen who trade Ivory from the straights of Madagascar. I was wondering about what type of buildings should i construct in my regions to maximize profits and keep happiness at good levels. Most of my territories don't include any sort of entertainment buildings. I have one or two here and there. So at what percentage should i build in each territory. For example 5% religious 5% entertainment 80%industrial? I pretty much just have 90% industrial and 5% schools 2.5% religious and 2.5% entertainment in the towns surrounding my region capitals. Also military governors. Are they any good? I don't really focus on them at all it seems like they are only good for outer rim near an enemy.

I also have a question about Indiamen. If i place 2 indiamen on one trading hub(madagascar west indies...etc) does it double my income of supply? or do i have to place indiamen one at every trade hub?

How does the trade market work? Does it work on exclusivity(for example say that im the only nation who is trading ivory at the moment) or does it work on rarity(say there isn't too much ivory in the market so therefore it's more expensive)
or a combination of both (your the only nation trading it and it's rare therefore expensive the market hasn't been flooded with this resource so it's expensive)
and does value have an effect as well (Example Ivory is worth alot and will always be worth more than sugar)

The game usually will do something to disrupt your trade. Everyone will hate you and they will do things to cut your money to nothing. Try it on a harder difficulty if it is too easy.

Indiamen are counted as warships I think, I could be wrong though. Usually it takes merchant ships to give you trade, I think. It has been a while since I played.

Trade vessels do not double. It gives you a grater percentage. I don’t remember the numbers. I think it is a combination of rarity and if you have a monopoly. It also depends on the number of trade partners you have and the number of ports your trade goes into.

If you are trading with a country that has no commercial ports you get no money from them.