How to make a J2E file...
I do not know if at this period of time it is possible. I know if you successfully made a J2E file that it would automatically appear in the list in Jazz2 (for example, if you got TSF and copied over a J2E file from 1.23 into that directory, that copied J2E would automatically appear in the list, thus I don't think there is any 1.23 to 1.24 changes). There probably is a way via some 3rd party program that has yet to be made...but I dunno.

I cheard that cinematics (J2V) work only when used in episode. Is that true?
Well, I'm not sure what you 'cheard', but I don't know what you're talking about. Perhaps you could rephrase the question.

How can I make sound in my J2V movie?
Reprogram Jazz2.

I'm looking for some people to help record voices for characters in my J2V... I can only talk as Jazz.
Nu can du for me, sorry.

do I have to ask all those questions?!
YES! SLAVE! LICK THAT LITTLE SPACE INBETWEEN MY TOES!