Rexsar, you're late, but try to complete it without using scripts, just by playing.
enable_cheats - hover the cursor over the desired location - Ctrl+T.
Regarding the saves - the Incas actually left right when I was recording how to defeat the vampires. So, they are overpowered there.
About the prayer - I need it because it gives a bonus to attack, defense, and +20% initiative for a couple of turns. (This is especially useful if you don't have enough mana to cast a blessing...).
About the level 1 units - if you didn't notice, all of them were getting wiped out when I was clearing neutral creatures (especially in the castle with the priests) - liches and banshees.
I tried using level 1 vampire units to defeat higher-level enemies - it's the same situation, but I managed to save 1-2 more warriors.
Regarding the troops (and infantry too) - my dear friend, where am I supposed to get more of them? I don't have any money, and resources are scarce. If I spend time clearing creatures, I'll lose the entire map because of the 4-week time limit. This is a hopeless situation.
I've already completed it using scripts.
I'll play the first mission in the evening and post replays of the key battles.
The prayer gives only 10 initiative and is not very effective at a low level - there are not enough troops, and its duration is only a couple of turns. If you're going to take it, do so when you have a large army and have already taken more useful perks.