Questions about mixing music with surround sound

I usually just mix my cakewalk songs in stereo and I do not think about surround sound much because I use stereo near field monitors to mix my music.
 
But I have been wondering what it would be like to mix in surround sound.
 
Can't I simulate surround sound in cakewalk and output it to stereo monitors or headphones? Do I have to physically have surround sound speakers to use that feature in cakewalk? I have a Roland quad-capture with four outputs.
 
Is there a benefit to the music to mix in surround sound or should i just keep mixing in stereo in my sonar output bus? I release my songs in mp3 or wav format for online music store sales and i have only ever released them in stereo. http://trexred.com
 
Does mp3 support surround sound?
 
Thanks for any responses!