1: Yep.
2: Ctrl+R lets you change default empire. Alternatively, in the upper left of most windows, there's a drop down menu to change empire.
3: As often as you need. The empires should be set up to not need constant attention. When something happens that requires a change (just keep an eye on the event window), you switch over, fix it, and get back to moving as quickly as you can.
4: Without access to designer mode/database, yeah.
5: The system window (f9) while in spacemaster mode.
6: The race/empire window (Ctrl-f2). I really don't recommend deleting the spacemaster empire though. It comes in handy if you ever need to use SM mode again.
7-9: I don't really mess with that stuff.
10: I don't think so? Haven't tried.
11: It would count up, if it works.
12: I'm not Steve, but as I understand your question, yes. Decide how each faction/whatever will behave first
13: No. You initiate attacks from the ground units tab in f2.
14: You haven't even begun to scrape the surface.
I'd suggest you look at ALL the different little windows available from the main aurora menu window. The spacemaster comparisons are useful, production overview is something else entirely, and all the summary windows are priceless when you can't remember where you left fleet #7. Also remember to take the events window and filter out events that really don't matter to you. There are a lot of poorly documented convenience features in aurora. Taking an hour to figure out fleet organization wasn't worth it when you only had a couple of fleets. In a multi empire game, the trivial bits of automation can save you hours. This is because advancing a single year will quickly take hours. If you don't have a lot of time to spend on a single game, you may not want to get into this. Just a word of warning.