Just a question here. By masturbation, and with a little water applied

at the appropriate moment, would Ranma be able to (literally) get
himself pregnant?

I've had this discussion before.  I would guess, he could.  Through
artificial insemination maybe, he could reproduce like a hermaphrodite.
Only problem is what happens when he turns back into a guy while
pregnant?  That discussion was here before, so I'll stop there before I
bring it back :)