norbyte

"Difficulty levels aren't finalized yet, but we have some ideas." http://www.kickstarter.com/projects/larianstudios/divinity-original-sin/comments?cursor=2588511#comment-2588510

Yes, you can create your own maps and modules.

NPCs (and PCs) are moddable, you can change existing ones or create new ones.

Spells: "Much of the balancing is exposed, including the spells. Some spells are even "children" of one parent-spell because they are much alike (think of them as a template spell), they just use different numbers and effects."

The learning curve is a bit steep for first timers; check this editor vid to get an idea of how it works:

http://www.youtube.com/watch?v=YG-PujUp-9Q

They answered this one in the KS comments: "when you join a game, it's the hosts characters that you take over" http://www.kickstarter.com/projects/larianstudios/divinity-original-sin/comments?cursor=2593603#comment-2593602