[Anthony]

Welcome to the shack.

I have never been fully clear on the conduit/in-wall code rules. If it is in-wall bare (no conduit) then it must be CL2/CL3 or one of the other listings (riser rated, plenum rated, etc). However, if it is in appropriate conduit some people just run regular wire in the conduit. I am not an electricial, just an installer, so I always err on the side of caution and run everything in-wall rated, even if it's in conduit.

As far as the wire goes, there will be no difference, for the same gauge and strand count. Higher strand count keeps the resistance of the wire lower in higher current situations and makes the wire more flexible. If it's the same brand of cable, but just in-wall/regular as the difference, then the wire will probably be exactly alike, just with a different jacket covering.

as for power back up: I have been thinking about getting one for my projector as well, but alas, it's still just in the conditioner only. I have had a few blackouts that had me worried, but for the most part I have not needed the battery. Monster and APC both make home theater power backup solutions for this exact problem. Make sure you go that route and not a computer backup. The computer back UPS are notoriously noisy (hum, some have fans, etc). APC went through great pains to get a UPS for home theater that was quiet, could take a large current draw, and that did not need a fan (or had a very quiet one).

good luck.
anthony