I didn't work with emacs.(Sorry there) For code editing, vagrant mounts volumes from the host machine, so you can edit the code from the host machine and it will update in the box too.

Suggestion: Almost the same thing you can achieve with Docker(containers). Because you have a Mac, you need to check the permissions to files that need to be written from both the host and the container.

Good luck.

P.S.: Not a DevOps, these are my 2 cents. P.P.S.: Don't kill me.