For 1. you should check out:
- How to customize reference style? - #4 by Siedlerchr
- Entry preview setup - JabRef
- Custom export filters - JabRef
It seems to be a little complicated, but maybe it answers the question. I agree that it is confusing why edit does not work and if it were to be intentional, maybe it would be a good idea for this to change? Would you be so kind to make an issue at github: Issues · JabRef/jabref · GitHub