1. All of the campaign variables are saved in the player's campaign save file, so there's no way with retail files to copy data from one campaign to another. So you'd either have to combine all three campaigns together or use a script to save data to a file that is independent of the campaign saves (I do have such a script working if you are interested!).
2. If you give a Mjolnir an attack order, it will try to face its target. The issue is that the front of a Mjolnir is actually its side (as you can see when you place it, its facing up instead of forward) and won't actually be able to hit anything. So either position is to the best of your ability yourself, or use a modified Mjolnir that actually faces forward (there are a few floating around, I know Vassago and BP:WiH Act 3 use them).