From what I can tell, it's not possible to be selective with signature display (on a per post basis) - however it is possible for members to disable signatures from showing if they wish (https://www.electronicspoint.com/account/preferences).
Saved drafts are temporarily stored on your PC using cookies - so if you go to the same section where you created the original draft thread and click "new thread", it will hopefully be there on the new thread screen.
It's meant to save text if your browser crashes or if navigating away from the page by accident (i.e. clicking back). I don't know how long the draft data is saved for, but hopefully it'll still be there.