Newbie re Wireless Transfer

I don't have a sophisticated system and very little experience in PC audio. I have read hundreds of posts but it is hard to understand if you are not familar with the products and terminology.

I am using Windows XP via usb to a Fubar ll DAC in to Audioengine A5 powered speakers. I listen to downloaded music occasionally but mostly streaming radio via WinAmp.

I am on a budget here and wondering

1. How I can improve the sound with software? I understand K-Mixer is to be avoided but I don't know if Foobar or any of the other players pass streaming audio.

2. Can I send audio from my computer to my main stereo in other room not only wireless, but on the cheap? I think Audioengine sells a set of dongles to do this but my main stereo doesn't have a USB input.