Unfortunately I belong to the group that does not, nor has ever been able to achieve multiple orgasms. In my younger days I could have a second orgasm after an hour or so, now we are talking 4-7 hours

I have only have had multiple orgasms a couple of times. Every time I did have one I didn't expect it and the one time I was jerking off standing up and my legs gave out and I fell into a wall . My roommate at the time came to the bathroom door and asked if I was okay I was like .....yaaa give me a sec. Other then that the closest I can say I have been is where I cum then fool around for 5 or 10 min then go back to having sex and cum again sometime during that session of sexy time. After my second orgasm it's pretty much impossible for me to cum again, I can have sex again I will just never finish lol

I have had a few that were 10-20 minutes apart but that involves some P-spot play from the wife with the first and sex for the second. This does not always work though, sometimes the second takes quite a bit longer.

Yes and rather easily at least in some circumstances. Pretty much any stimulation that i not penal i.e. nipple, anal, etc. Will bring me to non-ejaculatory orgasms (aka orgasm with no refractory period, as ejaculation is what trigger refraction). Vibration on the head of the penis will also do so (The Whal is my favorite for this link ).

I can also have multiple orgasm with stranded stoking penis stimulation but it is tougher. I either have to use very purposeful slow controlled stroke in order to orgasm with out trigger ejaculation or use my PC muscle to actually prevent ejaculation both of which require practice and concentration.

No - not happening for me. I've heard of men having orgasm without ejaculation - which can be repeated - but I've not even tried. For me orgasm and ejaculation are synonymous.

Need at least an hour or two between orgasms at my age.

I can have two, if I work at it. with no break in between.

Sometimes...
Some factors have to be present simultaneously.

It happens most likely in times I do excessive pelvic floor training or VigorRobic.

Bioenergetics (Alexander Lowen) helps to spread the orgasmic sensations throughout the body.

And a very slow rise of the arousal, slooooow... gives very intense, intimate non-ejaculatory orgasms.