1) Yes, using the containers from Proxmox.
2) config:
arch: amd64
cores: 1
features: nesting=1
hostname: ubuntutest
memory: 512
net0: name=eth0,bridge=vmbr0,firewall=1,hwaddr=12:A7:93:CA:04:E2,ip=dhcp,ip6=dhcp,type=veth
ostype: ubuntu
rootfs: local-lvm:vm-100-disk-0,size=8G
swap: 512
3) Yes...