You can permanently increase stats using witch bottles and servants however these are extremely limited, you can also increase your stats by adding more heroes to your active party so the game does get easier as you go since you can change your stats more.
As far as difficulty goes, as I've said it does get easier as you make progress but I believe each attempt is still a dice roll with stat increases giving better odds.
Last thing I'll say is save each day it goes right and load your last save if it didn't, it may not help the attempt number but you won't lose your money or obedience.