For just mixing tracks, I would recommend Acid Pro. It's very easy to use, and you can get pretty much all on top of your mix.
But, it sounds like you want something that edits wave files, too, and in that case, I would say Sony Sound Forge 7 is what you need. Mixing tracks isn't as automatic as in Acid but I use Sound Forge to mix tracks all the time. Acid can't edit the wave file (unless they changed that in the most recent version). It is strictly a loop sequencer, whereas Sound Forge is a fully decked out professional audio tool.
You can mix, record, manipulate, edit, effect, master, compress. Soundforge has filters for just about everything you would find in a hardware studio.
BUT, the plug-in to remove vocals and the noise reduction plug-in for hiss are purchased separately unless you can get them to bundle the plug-ins with your purchase. It couldn't hurt to ask.