Oh my gawd, you sound like an idiot!
You can be your own faction, you just need to attack some caravans to make the faction hate you a bit before you show up with an army at their gates. Can't have you going around storming castles whenever you want to, now can we?
I have no idea how to use shield bash, in Native Expansion it was right click and hold, then left click. It was pretty useless though, it just did a knockdown attack but no damage I believe.