I want to create 2 different constant wave of attacking Unit. But, i failed soo hard everytime

First, I want to create 10-15 Units, send them to random attack, once they all die, u want them to respawn and redo the same thing over and over.
So far, im able to create the Unit and send them to their death. But, they wont respawn. I dont know what i did wrong.
Second, I want to spawn 5 units every 15 seconds. And, send them on a random attack. And, redo this over and over.
So far, im able to create the 5 units but with no delay, they just overspawn at the location and the maps getting maxed.
Im also able to send them on random attack.
I use SCMDraft map editor, so easy to use

Thanks in advance for any help you guys can provide.
From a noob map creator
