I'm also confused about where mp and tp fit into all of this. For example, on the homeworld screen, when I select "Civilization Capital", it says Industry: 24 mp, Research: 24 tp. But what does this mean and where do these values fit in with respect to the "Military", "Social", and "Research" values I mentioned above?
Thanks for any help provided.
Yeah, it's confusing to me as well, but I can explain in my own way how I think it works, but there are things I simply don't know and have never seen mentioned here.
1. I have no idea how taxes are calculated. All I know is it depends on your population. I suppose if you turned taxes to 100% and then checked how much money you were making (adding back your expenses), you could find out how much each 1 billion people were worth.
2. Production % is how much of the tax revenue you receive each week (turn) is spent on social, military and technology, and how much is converted into money for you to spend (or be extorted out of).
3. No matter how much you put into Production, you can only get as much MP, SP and TP (Military Prod., Social Prod. and Technology Prod.) as per buildings you have set up for them. Your Civilization Capital on your planet has 24 in each, and every other planet has 12. So 100% Production and 100% Technology from the beginning means you get 24 technology points per turn (assuming you have 0% Research Bonus). Even your bonus production costs money, but only 1/2 the normal cost. A 60% bonus to Research would give you 38 TP (24 + 14, which is 60% of 24 rounded down) for 31 BC (24 + 7). Raising taxes will not affect this production, it will only pay for it. Lowering Technology Production will lower the weekly cost but give you less points per turn. Setting Technology spending to 50% would only give you 1/2 of your potential maximum TP. So remember a) When you plop a building down that gives you production, you will be paying for it for the rest of the game unless you set Production to 0%, and

Taxes won't raise or lower your Production, Production % determines how much tax is turned into Production instead of actual money, and Military, Social and Tech Production determine what percentage of your Production is used for MP, SP and TP respectively, and c) Whenever Social Production isn't being utilized on a planet, it's converted into Military Production (assuming your Military is set to at least 1%; when set to 0% this doesn't happen). Otherwise it's just turned back into money for you.
4. You need Military Production to build ships of any kind, Social Production to build improvement buildings on your planets, and Tech Production to make use of capitals and research buildings.