I'm afraid this is quite variable, so you just have to wait and see.
Also, it may change over time.   Certain things are obvious.  Anything
involving the prostate itself won't happen.   You won't ejaculate semen,
although you may ejaculate some small amounts of other fluids or even
urine.  The latter can be somewhat disconcerting, but as urologists like
to point out, urine is sterile and should cause no problems for your
partner.  Also, given the nature of the male reproductive system, it
would be astounding if there was never any urine mixed in with the semen
in a normal man.

Aside from the mechanics, the experience of an orgasm is in the brain,
and you can have an orgasm even without an erection.  Some men even
report that their orgasms are stronger after surgery.  Others find that
they don't have quite as strong a climax but rather a long pleasurable
buildup and then a relaxation.

It is normal for sexual desire to be weak at first but then build  up to
something like normal levels over time.

My advice is not to worry about it, take one step at a time, and adopt a
somewhat experimental attitude.  As they say, where there is a will,
there is a way.

Bobby,

Based on my experience, you should be able to experience an orgasm the same
as before your surgery, whether or not you are now capable of an erection.
Orgasm is triggered by the brain, not the penis. Without a prostate, you
will not have ejaculate. If you're like me, though, you may squirt some
urine as the bladder/urethra sphincter releases. Completely emptying the
bladder beforehand helps.

I've read the others' responses and all I have to add is that when I first
started having orgasms, post RRP, I had a burning sensation from my rectum
to the head of my penis.  As I was in ecstasy, it was not a problem.  It was
just a concern until I found it was not unusual.

I'm a radiation patient and side effects are similar but not
equivalent to RP.

Let me just be a devil's advocate and say flat out that anybody who
tells you that sex is the "same" or "better" after PCa treatment is:
a) full of crap; b) had a piss poor sex life before PCa; c) wearing
rose colored glasses; or d) all of the above.

Trust me:  as a physiological fact of life your sex life will be quite
different than before (duh) and likely not AS satisfying or intense.
Fact of freaking life.

That doesn't mean you won't have an enjoyable sex life.  Humans are
resilient and you will adapt to your new body. Different doesn't
necessarily mean dismal.  But being overly optimistic is, IMHO, a
silly and unrealistic way to face facts.  

Better to be pessimistic and be pleasantly surprised than optimistic
and profoundly disappointed.

That's my opinion and I'm sticking to it.

You're way behind the power curve, Bobby. Beside the fact that it's fun, the
sooner we get back to action, solo included, the sooner and MORE LIKELY we
will recover potence. It is vital that we take advantage of every
opportunity to work on the problem, beginning the day we dump the catheter.
Our erector set undergoes changes if left alone which decrease --
significantly if we wait too long -- the likelihood we'll ever regain
potence. My doc -- and the literature backs this up -- told me to go home
and have orgasms as often as possible if I want to have the best odds of
regaining potence.

Yes, SIR!!

Get off the computer right now and go have an orgasm. You don't need a whole
handful to get the job done. Tip: have a towel handy. You will squirt urine,
not semen.

I.P.

I was truly amazed by the feeling of my 1st post-RRP orgasm.  It was like
the doc rewired me - it was surprisingly quite intense.  It continues to be
very good.  Others have written that it's not the same - true - but
unbelievably to me, they're even better - and they were very good before the
surgery.

Sandy K.