What NAS to get for running plex and is there anything I should know?

I want to make a plex nas so I don't have to deal with Netflix and streaming services, here are some questions I have.

1. What NAS should I get? I've heard Qnap is good, but I want to know around what nas I should get
2. Is plex somewhat simple to setup and is there other software I should look at?
3. Is there anything else I should know?