It’s not exactly a single tool, but torsocks kind of enables doing what you’re describing. The syntax would be something like torsocks curl $url

1. This sounds like a weird one. It would be helpful to have some more info about your network. Would you share your PVE host’s /etc/network/interfaces file and the config file for the VMs (from /etc/pve/qemu-server)?
2. Excellent
3. I think ZFS would likely help since it can make use of block level snapshots. I think the way to move things over would be to create a ZFS datastore in Proxmox and then just migrate each VM’s disk.
4. Personally I think this is a bit simpler in an LXC container and there are a bunch of tutorials to help. These two are similar to my own setup:

• https://blog.bekh.fr/jellyfin-lxc-with-hardware-transcoding-igpu-passtrough/
• https://www.wundertech.net/installing-jellyfin-on-proxmox/

Hope some of that helps

Not sure if this is the kind of thing you’re after, but I think learning a little about the very fundamental pieces of these systems really helps to understand the mechanisms at work.

One place that was really useful to me was years ago, the Security Now podcast did a series called “How the Internet Works” ( I think). Steve Gibson went over all the principles layer by layer and it helped my understanding a ton. This was many years ago, so the rest of each episode is probably filled with really old security news, but the main bits are as relevant as ever.