And I mean it literally. Never played a Civ or 4X game before, but I fooled around with the demos for Civ IV and V and I seemed to know up from down most of the time, so my question is: what difficulty level should I use for my first couple of games so that I get some decent challenge but I don't get my ass handed to me?

Also, should I consider disabling the expansions (G&K and BNW) at first so that I can introduce the new concepts at a slower pace, or would that just deprive me of the improvements they're supposed to bring to the table?

you build up till you can go nuclear

I say just jump in the deep end. Keep everything enabled, set it to easy and go on a small map for a while til you get use to it. It looks over whelming to begin with but the tutorials that come with every step really help. You'll get the hang of it in no time. :)

That's your solution for everything ¬_¬.

I would start civ 5 by not starting it, and going with civ 4. I much prefer 4 over 5.

Disabling the expansions might help as it's your first run in the game.
Start at the lowest difficulty, when you've won or if you get bored, raise difficulty one level higher. If after the chieftain (easiest) you feel very confortable with the game, you can add the expansions because while they add much content which can feel overwhelming, it also brings a lot of great variety.

A great advantage of Civ is the presence of advisors. Don't hesitate to read what your advisors tell, you will learn a lot. Depending on what you want to do, follow what the related advisor tell : for instance, if you want to fight, read the advice of the military advisor.
Just turn advice to the max at first until it aannoys you. In my opinion,
Civ games are the only games where you can't get bored of the start (the exploration is really fun each new game), and late game can get old very quickly.

I thought it was shite...

And I think 5 is shit.

Yes we got that the first time... no real need to bring it up like a little fan boy though is there?!

Who is we? I thought there were one of you.

Personalities, we are many! Ignoring my point though aren't you.

You nuke Gandhi before he nukes you.

Bring one up, and I might respond to it.

That's why you'll never find me playing that crap.

I prefer the intellect and sophistication of a game like Carmageddon. These Civ games, they're just a bunch of cheap thrills and fluff with no actual content or merit.

If you're going to type such shite bog off to gamefaqs forums. I believe they are at your maturity level.