I am considering starting work on a world in CAW. However, I want to know something first: Should I decide to upload said world, which EPs/SPs would it need? (I have all EPs, High-End Loft Stuff, and Master Suite Stuff.) Can I control which EPs and SPs the world would need? Thanks!

You control what EPs you need by using the stuff from said EPs. Let's say you used the trees from WA and shells from LN, and nothing from any other EPs,then only those two will be required.

I'd suggest NOT using stuff from SPs, as they are far less popular, so using content included in them, would decrease te number of people downloading your world. As for the EPs, it depends on your idea. I, for example, am planing on making a all-in-one world, so that people don't have to place ugly lots in empty places to have stuff from other EPs. But it's up to you.

How do I know which stuff in CAW is from which EPs? I want my world to only require the base game and SN, so I need to know what to avoid.

In game it's quite easy to group stuff, just tick the EPs you want to use in Buy mode and Build mode. With CAW, it's a bit more difficult, you just need to know. The best solution is to check while in game, as the stuff in CAW and in-game has the same names. There's no better way I know of.

Thanks!
By the way, the reason I'm using SN stuff in the first place is because it's going to be a redesign of Moonlight Falls.

As I recall, any EPs which are installed in your game will be required for any world you produce with CAW.

Personally, I keep my CAW installation on an entirely different computer than my game. This way I can control which version of CAW I am using as well as the expansion packs required. Since I use lots of cc, I have found that versions of CAW starting with University are not friendly towards cc, or store content for that matter. To the extent that I want content from later EPs (eg a bowling alley, coffee shop, or marina) I can put them in a save game file.

That's what I've heard as well. I got the impression it changed at some point, now you have to uninstall the one's you don't want to use, or perhaps you can find a mod to control what EP to start a game on. I know one excist, but I haven't tested it myself. I use to refer to it as an Any-game-starter, but it may have another name now.

So when it comes time to run CAW I should just have the base game and SN installed?

Installing and unistalling is not reqommended, because you have a limited number of them from ea.
I would probably check out that mod or program in the download section

Perhaps someone more technical has another suggestion?

The limited number is a limit on the number of computers I can have the game on at one time. Thus, installing takes a computer out of that pool and uninstalling puts one back in. An uninstall followed by a reinstall has a net change of zero.

Ah, that's a new one. Most people in the game forum seems to think it's a limit on number of installations altogether, but then it doesn't really work like that anyways accoding to some. It being a limit on number of computer may actually make sense then That's what they have on Photoshop as well.

You just give the caw question some though, maybe you come up with a solution for you