1) The settlement is loyal to another faction so it joined it.
2) Garrison script.
3) + "disobeying orders" question -> BGR, which you installed without reading what it does.
4) No idea, doesn't happen to me.
5) Probably BGR again.
6) Victory is always a possibility. It just might not be a probability.
Did the enemy army see you prepare the ambush?
Accepting the various events can give your agents good traits.
The Pope orders both factions to stop fighting. Retreat to your own territories and just defend yourself. Give the Pope money so he favours you.
Please don't insult us by assuming we wouldn't know where the quote is from.