It lists all the NAS units and which ones can do what thing (eg: 4k and transcoding etc). Come back with questions after having a look.
Internet up speed is relevant if you want to share Plex with your friends - I think that speed you quoted (I assume mbps) means you are on a full-fibre (gigabit) connection, but check your up speed. You can do this simply by going to https://speedtest.net from your browser (whilst on your home network).
You will need to be a little more specific about both your media format and which (smart?) TV’s you have if you want to find out if Plex needs to transcode to them or not.,