AFAIK you can't have different qualities (4k/1080) of the same movies/series on the same instance.

I hate when any company I'm buying something from does this.

Debian and docker compose

Specific to your proxy issue, I'd highly recommend nginx proxy manager, it's a gui for nginx and helped me with a lot of issues getting other proxies to work initially. I still use it a couple years in simply for the ease of use

It's kind of mandatory for windows unless you want to get viruses/malware.