Xen with Gui Guests

[GOS]

Hello,

actually I use virtualbox, but for a bunch of reasons I think about to switch to KVM or Xen. (Sorry, if I choose the wrong subforum)

For Xen it is not easy to find out, how GUI-Guests (with Desktop) can be used. VNC seems very crappy, while it is quite unclear if SPICE will work or not (the Xen Wiki seems outdated and is a bit unloquacious)

Therefore my questions are:

1) Are there better options for Xen then vnc? (My VM's are Gentoo, Windows 7 32Bit, Windows 10 64Bit, MS-DOS)

2) It seems that SPICE will work for HVM (PVHVM) guests, but does this work for newer Windows versions?

3) Will SPICE work with Gentoo in PVH mode?

4) Is gentoo in HVM (or even PVHVM) mode much slower than in PVH mode and can gentoo use spice in HVM?

Thanks in advance and kind regards
GOS