Two Newbie Questions: (Priest level & Assassins)

[Michaelangelo]

Two questions:
1. Aside from creating a prophet unit, how do you raise the priest level of a unit? I saw a chart somewhere in the manual (which I can't find again for the life of me) that showed priest levels up to 5, but I've never seen anything above a 3 in the game, and that was for a prophet unit.

2. I've had several assassination attempts made on my commanders and each time my commander disappears from the map, even when I won the battle. Is this supposed to happen or is it some sort of bug?

Thanks!