Compo Rules

So I participated in the compo the first time last weekend and came up with two questions about the rules:

  1. Do I understand correctly that I can't use publicly available assets, which are not made by myself, like music or graphics at all in the compo, even if I opt out of the respective categories?

  2. Do you let people alpha-test your games before the deadline, to get some feedback for balancing and polishing before handing them in?