(again, sorry for the English, my German isn't good enough to try and write - you can reply in German if you please

I'll understand)
I'm about 8 hours into the game but there's still plenty of questions that I haven't found the answer to:
- at the start of the game, I sold all my edelsteine and ertze but I wonder now if they have any use?
- I've picked up a lot of formules - how can I use them? Can they be used more than once?
- will I always have to go to people to have potions and other stuff made or will I be able to do this myself later in the game, without the need for other people?
Thanks for your help
