More of a food for thought question, but theoretically, could space expand into itself? As far as I understand it isn't expanding into anything particular, like some sort cosmic container. Just trying to conceptualize

That's what it is doing basically yes. If you want to be more precise look at the metric expansion of spacetime.

Have to visualize the space or distance between stationary points as growing. That's what is happening between all the superclusters.

Can definitely be hard to conceptualize.

https://en.m.wikipedia.org/wiki/Expansion_of_the_universe

I found it easier to think of as density decreasing (on average) rather than space expanding. 

This naturally leads on to the idea that the universe is cooling (by analogy with the gas laws).