If anyone else gets into a state where XCP is stuck in maintenance mode, and the only thing it will do when you try to take it out is to tell you that the host is disabled until reboot..
Then do: sudo service xcp-xapi restart
Bingo! (at least for me)
If you lost your guest templates, the list will be empty in XenCenter and if you do "xe template-list" nothing will appear.. do this:
If your Storage Repository won't let you create it, check to see if one exists in the LVM already and then use that one. (I may update this later with more details, this part is fuzzy now I'll have to recreate it)
The VNC session in XenCenter might not work when you use the keyboard. Don't know why, but if you close XenCenter and open a VNC session with another viewer, it seems to work. I opened one remotely from my X session and it worked fine. Although the viewer I used kept closing when the OS I was installing kept messing with the display settings.