This is a fantastic video on DIY bass traps, as many as you can in all four corners as funds will allow.
http://www.youtube.com/watch?v=***********
(I don't know why the link won't work, go to You Tube and type in "bass traps", it should be the first video)
A cement floor is nearly as good as a wood floor, I wouldn't spend the dough on wood, but I may suggest ripping up the carpet.
Keep your mix position centered in the room, with the long dimension positioned front to back (not left and right), and kill any early reflection points on the walls and ceiling with broadband absorbtion, as well as the wall behind your mix position.
As far as speaker stands go, the more mass the better. Cynder blocks are a good "on-the-cheap" option, but outside of that; if you're gonna buy something make sure they're solid.
Only after your room is treated, would I worry about any equipment upgrades, as you won't realize the potential of any gear in an under-utilized space.
Have fun, and don't do anything until Glen and Ethan chime in with their opinions.