Questions for those more knowledgable than me(so almost anyone)..

[velk]

You get 1 commander for any province defense, with an increasing number of troops up to 20, when you get a second commander, and any points above 20 will give you some additional special troops. Which troops you get for which nation is in the manual near the front IIRC.

As a note - if you are playing Ermor, Marignon is your worst enemy. For beginner games you could try playing without them being in the game.

As far as I know, soul gate priests don't require any corpses to use their summoning abilities. Just set them to summon and they will happily remain cranking them out.