https://join-lemmy.org/docs/administration/administration.html
Lemmy uses roughly 150 MB of RAM in the default Docker installation. CPU usage is negligible.
Highly depends on the people using the server. If it's for you and a few friends, even a Raspberry Pi 2 can do the job.
Only me.
Pick up a raspberry Pi online and head over to ! selfhosted@lemmy.world also get a domain from somewhere.
Be warned one you start the self hosted game it becomes an addiction. First Lemmy, then a Plex server, then a search engine, then a mail server. Eventually you will be a mini personal google.
I have a personal instance I run for stuff like testing bots, so it isn't very highly federated (I just sub to a couple communities to make sure it is working). However, I just checked and the whole docker compose stack is using 250 MB of RAM and ~1% CPU on a single core VPS and consuming ~300 MB of disk space.
Of course YMMV depending on how much you use it and federate.
