That sounds suitably cheesy. And I don't know the status of every D&D monster, or where to look it up. Elves, dwarves and dragons are from mythology. Other fantastic creatures might need to be double-checked.
It depends on how similar they are to the source material. It doesn't matter if your fan work is free. I can't tell you much more than that; you'd have to consult an intellectual property lawyer. You're probably in no more danger than any other fan artist, for what it's worth.
