Yes, these are good ideas.
* Copy tree.
This is something which would be very useful. I have in mind a "question scripting language" which would make this trivial.Lots of work, and it would have to parse into the tree structure. This would make a great project for a final year computer science student. Any takers?
* Copy test. Good idea.
* Numerical answer test. Can you specify what you want here. Since teachers rarely agree on "how many points" we'd need a neat way of expressing this. I'm happy to consider this.
*Enable mark: I've tried hard to avoid this kind of thing, but am not dogmatic about it...
I guess from all of these you'd really like to write lots of Maxima code directly to get exactly what you want in each question. This is fine, up to a certain point, but makes error trapping very difficult as you generally only get "it didn't work" from maxima. Much of the work in the PRT is robustness and recovery. The PRTs also create a trail of notes, which you'll need for analysis. The constraints are there for a reason, but they do come with an overhead.
* Copy question from quiz is definitely a "moodle thing"!