I was wondering if my Ryukin (Drumstick) will be able to mate with my faintail looking oranda (nugget)? Thanks.

Yes all goldfish can interbreed as they are the same species

That and more! My large comet was not one bit bothered by the fact that all the girls in his pond where koi. He didnt mind chasing them at all!

Yes

hmmm...sounds interesting

Sure!