>>272631320
It's relatively simple, in relation to other things you can do in unity for vrchat worlds. I don't know of a prefab or tutorial off-hand for 'quest optimized' mirrors, but the #worlds channel in the vrchat discord can help. Just messing around in unity is fun too, most general unity tutorials you can find on the internet apply.

>>272631317
You can spawn the camera, or other stuff that's baked into the avatar you're using (with various hacks), but that's it. You might like Anyland, where you have a whole inventory system of props you can spawn anywhere as well as save stuff from worlds. Or NeosVR, where you can literally drag 3d models or movies or pictures out of your hard drive and into the world.