1. Currently, you can only use 16 text strings in a level.
2. It has a lot to do with that event. In a multiplayer game, any player on a No Fire Zone event will be unable to shoot. Of course, you will be unable to place other events directly on those tiles, but belts can help you get objects into there if need be.
3. 1023 each. You could have figured this out by typing numbers into JCS and seeing what happened (although I will admit that particular error message is radically unclear).
4. Events like those aren't really meant to be able to respawn and JJ2 can't do what you want it to do here.
5. Article. The warning in there about the Switch parameter should nowadays be modified because it works fine in JJ2+, and it works well enough in regular JJ2 that you should be able to get away with using it in most situations.