

This mostly comes down to your preferences, but my rule of thumb is that everything should be on mgmt vlan for mgmt, and then you choose which of those to expose to other VLANs via secondary interfaces. This has the benefit of allowing configuration when you’re on the management vlan only, and limiting access to the service itself.
Depends if you’re hosting something public, or something private.
For public, a webserver is a simple start. Can be anything you want it to be, but as complexity increases, so does the amount of potential attack vectors, so keep that in mind of you’re considering adding things like WordPress and the like.
For private, a NAS and/or a simple game server is a simple and useful start.
As for how, there’s a million ways to do it, and I’m an old stubborn BOFH that still cling to the old ways of doing it (as in, no VMs, no containers), so I’ll defer to others for that.
While purpose built server hardware is always nice since it comes with some useful additions, the truth is that “any” machine will do. Old discarded PC will do just fine.