@Dreadnought: My first piece of advice for you is to read
Ision's article on Wonder Addiction.
Dreadnought said:
1. Do I build graneries in every city, even those who wont grow beyond 6?
Granaries are not quite useless in cities that won't grow past size 6. Granaries are most useful in the cities that will be losing population from making settlers. Granaries are essential in "Settler Factories". In the early game, build a Granary in settler factory towns...
2. Should I build barracks in every city, or should I build it in every other city, etc.
Nope. Your settler factory doesn't need a barracks. Any towns you set up as "worker pumps" don't need a barracks. Try this: when you are settling your first few cities, pick a site with nice shield potential... bonus grassland and such. Build a barracks there, and no other improvements. Build nothing but units there.
On a related note, bombard units do not have "veteran" status. so a town that produces 3 or 6 shields per turn can make catapults and still contribute to your mililtary....
3. Marketplaces and banks: which cities should I put them it (like size 7 and up cities, etc.)?
Marketplaces are the most under-rated improvement in the game. Build markets in any city capable of growing past size 6. Scrap temple/cathedral builds, and build marketplaces. With 3-4 luxuries hooked up, markets are more powerful happiness producers thant Temple/Cathedral, and the commerce is powerful. Build Banks in cities that are ~70% productive.
4. Should every costal city have harbor and/or commercial docks and what cities do I build airports in?
Buld airports in cities that will build air combat units. Build commercial docks like banks; in productive cities. Build harbors in cities that buld naval units, or need food from the sea. "Fishing villages" on the edge of tundra can (eventually) make some decent gold...
5. Should every city have all three science improments: libraries, universities, and sci labs, or should certain cities not have unis and sci labs (i allways have libraries in all of my cities)?
After scrapping all your temple and Cathedral builds, build libraries for culture. Build Universities only in your more productive cities (and I mean CITIES, not size 6 towns).
Also: in every city sized 6 that has excess food but is not near a river or lake, should i build an aqueduct?
YES.
Finally: City Spacing: Each of my cities radius' are touching at least the square next to another city, is that too close?
Probably not close enough. You'd be surprised how powerful tight builds can be. The key is to use as many tiles as you can. If your cities are all spread out, many tile can't be used by citizens until Sanitation and Hospitals.
if this has aleady been asked, im sorry).
Now there you broke a rule. This is a thread for asking questions, so you're not allowed to apologize for asking questions in a question-asking thread. You now owe us all an apology for apologizing. (I'm kidding

)
Welcome to CivFanatics!
Edit: I noticed your postcout was up there a bit...so it's a bit late to 'welcome' you... but the thumbsup still counts.