Volleyball is now rally scoring, which means a point is scored everytime the ball hits the floor. Indoor goes to 25. It seems that beach goes to 21. In IL, even the high schools are playing this way and can use the libero too. All these rules start at the Olympics, then filter to colleges and finally to high schools. I think the last Olympics (maybe more) used rally scoring to 25.
A side out is when you get the serve back. You're right, it used to mean just that. Now a side out also scores a point AND gets your team the serve.
You still have to win by two, but at least in h.s., we've found it's hard to have a big comeback now.
Did I get it all? Let us know.