On several occasions, I’ve had orgasms without ejaculation, as well as ejaculations without orgasm. I’ve also had orgasm and ejaculation without erection. I don’t recall either one of us doing anything special; I think it depended on the circumstances. Next time it happens, I’ll try to remember to take notes.
I don’t know, but I can continue with sex after both orgasm and ejaculation, sometimes getting there a second time 
Small boys of a certain age who masturbate have orgasms without ejaculation - I’m told.
Last night I visited my gf and we spent hours working on answering the OP. Somewhere along the line I lost all of my notes, however. Looks like I will have to attempt to reproduce the experiment. Oh, the rigors of science. 
If you work on your kegels regularly, it can improve your sexual stamina. I encouraged my boyfriend to do this. At first, he was just able to more easily control when he had an orgasm. Then he got to the point where he could have small orgasms without ejaculating, then a big finish. Now he’s working on multiple small ejaculations without losing his erection between. I look forward to seeing what he’s learned next time he visits.
Hope you’re being careful about that “reproducing” part.
My girlfriend manages… unfortunately 
hehe…good one. In place of “reproduce” I should have said: carbon, clone, copy, do again, dupe, duplicate, echo, emulate, engross, follow, imitate, knock off, manifold, match, mimeo, mimeograph, mirror, parallel, photograph, photostat, pirate, portray, print, re-enact, reawaken, recount, recreate, redo, reduplicate, reflect, relive, remake, repeat, replicate, represent, reprint, restamp, revive, stereotype, transcribe, type, or xerox.