1. There's lots of threads on here discussing VPN providers. PIA, NordVPN and ExpressVPN seem to get decent recommendations depending your needs. ExpressVPN are the only ones currently able to geo unlock Netflix US if that's important to you.
2. I'm assuming then you want network wide VPN coverage? I know Asus routers come with VPN clients and are not bad, and there's lots that can be flashed with Various custom firmwares that will do the job. Not that I have personal experience but I've seen mikrotik routers recommended as good, cost effective routers. Be aware network wide VPN coverage is very CPU intensive and so most consumer routers won't be able to use all your bandwidth and encrypt/decrypt traffic. For this reason Ive built a pfSense box that has no such limitations and does a whole lot more besides.
One other point. You say you don't mind if your VPN takes up a bit of bandwidth. This implies you are only going to use the VPN on your torrent box, in which case you don't need to worry about your router choice for VPN really as the end device will be doing the heavy lifting. If you want a router that acts as the VPN client but tunnels multiple specific devices and not others then you're into the world of policy based routing and there's not many consumer devices that do that - you'd need something like pfSense.
3. There's no real setting up of powerlines. Plug one in downstairs, plug one in near your router and you're done. They suck though. If you can in any way run a cable it will be better.