You randomly loose 1-4 stat points (most often 3) from the vampire if you save the boy. There are 2 level bonuses in the game and a 5 stat point bonus from the shrine of good and evil (save first, as it can also give a 5 stat point penalty), so I wasn't too worried about the loss (I had lots of charms and equipment with empty slots I never used). That said, technically I'm not sure it is a great trade for a bit of experience, reputation and a level of Bless, if you are not role-playing a hero.
You need to be in the high teens or early twenties for character level to handle the cursed abbey and surrounding area (though it is easier to take out the zombies with a ranged attack). Spell Shield helps with the zombies' poison attacks, since the damage comes off the shield, and you don't jerk around with reduced offensive and defensive capabilities.
The graveyard above Nericon's garden was designed to be cleared after you had been to the castle (after a detour leaving the castle, that is where you end up). Before the latest update it could not be lockpicked (though the Nericon's garden key would open the gate, and there was a duplicate key in the Ars Magicana potion dealer's back room, though it is a little tricky to get). I did most of the quests in Rivertown and Verdistis and cleared the Rivertown sewers before entering the castle, so had no problems with the graveyard.
