To answer your questions:

1. There would NOT be any usage restrictions on the item.  The person can certainly sell it here in Renderosity.

2.  For the character and parentable props (letting the artist sell it to others), I was thinking of about $35-$40, but I don't know if this would be a fair price, because I have never done this before.

As for a deadline, this is something I don't need right away, and can certainly wait.