"we are the space between every experience and therefore also the experience, as it is all occurring in that space"

That's a very good way to put it. (I'd perhaps also add that that space, too, occurs. But that's just a technicality.)

"Is self realization akin to enlightenment or is self realization a step, a must, towards actual enlightenment?"

Enlightenment, self-realization, nirvana, moksha, liberation, entering kingdom of God, etc. -- they are all one and the same. (The realization will most probably come in some steps, depending on the individual in question, but all those words denote the "end result" that is identical.)

"What does remain after all is set aside.. Being?"

Yes. And clearly, you cannot separate yourself from it. So, who is "I" when you are that being?