The fight with Dhoulmagus is just above half. The medicine for Dodgey dave is just that, Special Medicine, out two strong ones in the pot and there ya go.

Yes, you need to go to the church everytime you wanna now about next LVL EXP. No you can't get all the abilities I think you're able to max 2 sets of skills, which for the hero needs to be swords and courage. Each character has the same amount of skill points, a few of the faqs and threads on www.gamefaqs.com list alot of the character info.