If you’re interested in creating your own missions, the best method for that is probably to head over to the tutorials section of the forum and take a peak at the documentation. I wrote a post on where I personally felt is the best place to get started here.
Lemme know if you run into any major issues with creating your own mission in this thread!
I've thought of this for a while, good idea. I think the new added Additional Script Functionality could accomplish this, apart from of course time travel.