Welcome!

As for the former: I guess it depends on what you consider "technically possible", but it is. It's not easy though, as all the new screen area needs some place in memory, and JJ2's memory management wasn't written to accommodate so much graphics data.

There are already some commands to limit resolution, e.g. /maxresolution.

As for the latter: more advanced rendering is being worked on, but obviously it's a fairly large project (lots of things to replace/edit), and as such it's hard to give an estimate for when it would be done.