I was wondering if you can post a drawing of an image that already exists. I draw traditionally with pencil, pen, and paper and I've redrawn a decent amount of images. To some it's "copying" but I spend several hours going into detail and redrawing various hentai and ecchi images.
Can I post these here? If so, do I basically copy the original image's tags (when appropriate) and add the "third_party_edit" tag?

If it's good quality we allow it. We have the derivative_work tag for stuff like this. All the other tags are the same. If it was just an edit then only the original artist is tagged. For a derivative_work , you can be the artist tag or both artists are tagged. I don't think going from a digital medium to pencil on paper counts as an edit.

Does allow sprite sheets to be uploaded as well? SFW or not?

Ok cool, thanks for clearing that up