1. stls are bad actually
2. model needs to be designed for print from the start
3. yes, properly designed ‘ready to print’ models can be great, yet there is still a lot of variance in printers’s capabilities that will require at least some time to configure in slicer

This is the way to do it in my opinion. There is always an old computer laying somewhere in your house.

I’ve found 100% infill weaker than something like 60%, it won’t break per se, it would delaminate. Also number of walls is really important you can dial down infill to 20-25% if you have 6 walls or more.

Don’t expose jellyfin to the internet is a golden rule.