I wouldn’t personally recommend the official link cable — it’s expensive, and in my case it was flaky. I’m currently using a cable made by Cable Matters[0] that works well.
Most people buy the Steam version, though either can work. I personally lean more towards Steam so if I change headsets to something non-Facebook (like Valve’s rumored upcoming quest competitor), I can still play Beat Saber without a second purchase or weird hacks.
For installing mods, ModAssistant[1] has worked well for me. It’s pretty foolproof; the “standard” mods are pre-selected for installation by default, so for a minimal setup just open ModAssistant, point it at your Beat Saber installation, and install the standard mod set. From there you can search and install custom maps in-game.
I don’t have too many other useful links for you, but r/beatsaber on Reddit is pretty active and good for asking questions that haven’t already been covered by that subreddit’s wiki.
[0]: https://www.cablematters.com/blog/Virtual-Reality/oculus-que...
