Wave Shooter with State Machines

I am new to this forum and am lost to whether I’m in the right place but here I go.
I am doing a First Person Wave Shooter and as for now I’ve managed to make the basics working such as health and magic points (yes, it’ll have magic instead of fire weapons), enemy spawning and such.
Now I am thinking of the many states the Level would have, like “in round” to make it spawn the amount I preset it to, and that gap of “many seconds” between rounds for the player recompose and buy stuff around; also I’d like to have a state “dead” so the player can restart the level or go back to the title screen. How would I do that?
Also, I want to spawn random children of a Enemy Blueprint parent, how’d I do that as well?