bbqnj,
Just do a search or americas barbecue, there's a few recent posts here about them. Resellers many times will undersell the manufacturer, but it's still a CS.
Nope don't have any pictures immediately available, but it's pretty easy to figure out. Check the grate size of the SM's and if you know the size of the butt you can figure it out.
Three shelves, two on each shelf is 6. depending on the physical size of the butts, not the weight, you might get more or less.
If you're planning on doing that many, you might think about the 50.
A read through the owners archive and owners forum will give you a lot of good information if you're still undecided.