I use the NCE system, and for a beginner, the NCE Powercab is a good beginner system that can be eventually expanded. Price should be about $140 on the street.
As far as sound decoders are concerned, I think you can get one to fit this. I have the same loco, but do not have a sound decoder for it yet. One of the vendors told me there was a sound decoder that will fit, but I can't remember which one it is. It *MIGHT* be Loksound, but I don't remember.
Soundtraxx, I think, makes one that has the matching plug, but you have to disconnect one of the wires to go to the speaker. Come to think of it, you have to do that with the Loksound as well, if it has the plug.
Kennedy