I vote for CycleOps. It's what I have, and they have fantastic customer service. You get a lifetime warranty on the resistance unit, and if they change the technology and you want to upgrade the unit, you can do so cheaply. Great company, and since you're looking at all good fluid units, something like that would be a tie-breaker for me.
As for carpet, it will be probably be ok, but there are some things to think about. Is the carpet thick? If your trainer (which is fairly heavy) is going to be sinking into it a lot, then your rear tire could rub on the carpet, which won't be good for your training or your carpet. You'll also want a riser block or a thick book for the front tire to keep your bike stable.
Finally, is this carpet stuff you care much about? Gunk from your chain, dirt in your cleats, all potentially bits of rubber from your rear tire all will probably wind up on this carpet. You can get a hard rubber mat to protect your hard floor or thin carpet. There are several to choose from. Many of the companies that make trainers and rollers will make some kind of floor mat.
As for the indoor cycling class, you can use platforms. It'll be good to use some kind of clip or strap if you're going to be doing any work out of the saddle. Plus, trainers can also make any dead spots in your pedal stroke seem more pronounced, so being able to pull up will make the ride go more smoothly.