Regarding dynamic resizing, I’d advise to use Spice protocol:
- In your guest Windows VM, install Spice Windows Guest Tools – spice-guest-tools-0.100.exe
- Set your Windows guest to use the SPICE driver for display (in Proxmox, under the Hardware tab)
Compared to VNC I’ve found this is much faster and I don’t have cursor offset problems.
For more details see:
https://pve.proxmox.com/wiki/SPICE