I think you can just take the text of a license like Creative Commons but modify it to say that you're not giving permission to use your content to train AI.
However, if you go this route, remove the Creative Commons name from the license. CC does not permit their name/trademark being used on less permissive licenses.
Yes, but portals violate basic physics anyway.
A portal that faces downwards into another portal is effectively a perpetual motion machine. Drop a ferromagnetic object into the loop and wrap some wires around the loop, now you have an infinite electric generator.