Hello,
2) Aes is indeed useless for itself but it's great for trades. Also, it's "useless" also for the AI so it can be traded without worry. A minor bonus is the Shwedagon Paya which could be used for an earlier Free Religion (the +10% research is awesome early).
Nationalism is just like Aes, useless but great for trades. It's the most expensive (2900 beakers) and leads nowhere (for space race) so again it can be traded. Also, it leads to Democracy skipping Literature. I forgot to write that after Nationalism I stop tech trading. NEVER TRADE A TECHNOLOGY NEWER THEN IT. For the simple reason that the Internet will give it to you for free.
1) For this reason I don't follow that guide on space race, since you have the internet the most logical thing is to go to Fusion ASAP to get the free Great Engineer for a possible golden age, most of all the other techs will be provided by the internet, or they can be researched in 3-4 turns.
So my space race is very simple: Computers for Internet, then Flight/Satellites for Apollo, then Composites so that you have something to do during research (e.g. building those 5 casings) then go straight to Fusion, then research (or get it via internet) what is remaining, usually Genetics.
Doing so it's impossibile to lose the race, but I can lose by U.N./culture/domination.
3) The win is peaceful, but the game is not. 2-3 defensive wars are common, and they are great since they bring the Heroic Epic plus some generals. Barracks (I'm not 100% sure) increase your power statistics and allow to produce unit in all towns.
4) I don't have an answer. After you make cottages, you need some production (mines, then windmills or lumbermills) to make the standard buildings, (since you cannot abuse slavery, since you need citizens for cottages) and there is no room for anything else.
It seems to me that specialization = farms, for GP or extra production, but farms are the worst improvements in this strategy.
5) Well, they can be researched in any order, depending what you need first. If you don't have any happiness resource then Monarchy is top priority, to grow with HR.
6) The strategy itself could be called "delayed great people". After all, it does not change anything to make them later. Using a GP to bulb a 500-700 tech seems to me a waste.
6a) Not always: at Liberalism the best secondary cities produce 40 beakers so an extra Academy would bring other 20. But.. the same amount can be produced by a settled great scientist in the capital ( 6*(1.0 + 1.0 + 0.5 + 0.25 + 0.25 + 0.10) = 19 ) e.g. (Base + Oxford + Academy + Library + University + FreeReligion), plus the extra hammer(!).
Later, extra Academies would be better, but still inferior to a 1800 bulbing or an extra golden age.
If I have an "automatic" GP farm, e.g. all cottages and zero/one mines then I usually settle the first scientist, academy the second, then bulb or golden age the followings.
I build a secondary Academy before Liberalism only if I have a rich secondary city (gold, gems, dyes, etc.) with 60+ base commerce.