Hey Jonathan,
One of the drawbacks of the 15-1994 over the Cinema 7 is that several device codes had to be dropped to make room for the additional Radio Shack device codes (for Optimus stuff), and it appears that those RCA codes are among the ones that got dropped. I tried all the codes you printed on my Cinema 7 and they were all accepted. So, you only options for the RCA are to either learn the commands or get a Cinema 7 remote.

Regarding the device keys, this is one of the most frequently asked questions, and the answer is "no", you cannot assign a function of any sort to them. Regarding those annoying input select buttons, see my post on this page dated "08/16/00 09:24.34" for an idea. Maybe you could use the 1S button to selectthe AMP's input and the 2S button for the TV's input.

Rob.