11k is going to be too fast... You want to get your wheel's surface feet per minute speed to right around 5,000 SFPM. A 6" wheel on a 3450RPM grinder/buffer will get you right around 5400 SFPM which is close enough.
I cobbled up a quick javascript wheel speed calculator a few weeks ago. You can check it out here and try out different RPM and wheel diameter combos.
Buffing Wheel Speed Calculator
(if it blows up your computer, it's not my problem. eheheh)
I use a flex shaft for wheels. They're too damned heavy to hold up to the buffer and I guarantee you you'll slip and ding the wheel somehow doing this. (Been there, done that more than once) Get a flex shaft you can connect to your buffer/grinder if you own one. A good heavy duty drill can be used as well. I use 4" wheels on my flex shaft for two reasons.
1) It slows down the cutting rate and gives you better control.
2) If the wheel catches on something, it won't wrench on your wrist quite as bad as a 6" wheel will. (remember, I use a 1hp 3450 RPM buffer. It's got a LOT of torque - A drill will probably not have enough "oomph" or RPM to push a 6" wheel)
I wrap the end of the collet with duct tape to protect whatever I'm working on. As careful as I try to be with the shaft, I sometimes get the metal parts in contact with the piece I'm working on. The tape helps prevent inadvertent damage.
As for compounds, I buy the jumbo bars and they last quite a while. I did have one PITA part a couple months ago that ate up 4 6" sisal wheels and half a bar of emory, but that's not by any means normal. (Crappy aluminum)
1 bar of each will do those wheels a half dozen times easy.
Feel free to drop me an e-mail to skiddz *AT* adelphia *DOT* net if you've got more questions.