Who should I play as

[King]

Saxony is a very nice place to start. As you are part of the Empire no one is going to invade you but you do not hold any of your De Jure duchy for historical reasons and there are titles to create as well. Give you time things to do while at the same time having the Emperor to protect you.

 

[GAGA Extrem]

Ok. I'll give this some thought. Quick question I had from the demo. How are reinforcements handled? I seems like it's similar to Europa, but I'm not sure sense you don't have "units" in the same was as that game.

Raised levies will not reinforce on the field. Only mercenaries will do so.
However, if parts of a levy die, the home province will slowly refresh it there. If the levy is completely annihilated or dismissed, it can be raised again in it's home provinces with all men that have already reinforced there.