Any text editor supporting editor config for basic rules formatting is a good start
A GitHub account
Same recommendation for the dev env than running XO from the sources: NodeJS 8 and yarn
That's pretty much it.
The new standard way to import is here: https://xen-orchestra.com/#!/xoa
Let me know if you have any issue. It's still in beta yet, and we got one small issue to fix (it won't fetch the XO username/password, so it's still firstname.lastname@example.org / admin)
That's normal. If you boot the replicated VMs, then blocks will be changed. It mean no further delta replication will work on this VM. Force boot it if you lost the original VM and you don't care about delta toward the copy anymore. If you just want to test the VM without doing a new full (breaking the delta chain), boot with a copy. I think I explained that in this video: https://www.youtube.com/watch?v=FfUqIwT8KzI
That's a display glitch.