Rabies:
Yes you can plug into a PA system. Axe II gives XLR and 1/4 unbalanced line level outputs so you can feed PAs, mixers, power amps, guitar amps, reel to reel tape machines, ADAT machines, etc...
Yes you can clone presets, just save the preset you want to copy to a new location. The original will still be there.
The XL has 512 preset locations (Banks A, B, C, and D). Mark II has 384 preset locations (Banks A, B, and C). There are 384 factory presets, so the last 128 (Bank D) on the XL are empty from the factory. You can over write any of the locations with user presets.
You can see a list of available amp models in the users manual or on the wiki page. I'm not sure about a list of the factory presets. Probably on the wiki too.