I hope everything works itself out, I know it's hard to lose those birds that are dear to us.
I wouldn't eat the drake, he just seems to be acting like a normal drake, not an aggressive one at all. Now if he was attacking you or anybody else, I'd cook him up in a heartbeat because I don't tolerate animal on human violence. Pekins are bred for commercial use, so they are bred for that sex drive. That way commercial companies only have to keep minimal amount of drakes to cover their flock, it is the same reason many purebred commercial roosters tend to be fiesty, vigorous breeders. Getting more ducks will help, but if he isn't riding his girls bare or drawing blood or actually attacking the chickens, I wouldn't worry too much about it. More ducks means more fun though! I find my ducks very fun and addicting, I still can't believe I've accumulated 13 and rigging my refridgerbator to hatch duck eggs. Fun, fun!
-Kim