Trying to fire one projectile at a time


I’m almost a total beginner with unreal engine and game engines.
I’m currently working on my first project ever, and I would like to be able to fire one projectile at a time, until it is destroyed (or until a delay if it won’t destroy).
I’m having trouble with blueprint communication, I don’t fully understand how the ‘cast to’ node works.
I also want the player to teleport to where the projectile is at the moment he presses a second time the ‘fire’ button, if the projectile is mid-air.
Here are some screenshots of my attempt, i’ve been stuck with the ‘cast to’ node for a few hours.

Thank you in advance for your answer !

Alright thanks to you it’s almost working ! You’re really helping a lot, but I have one last (I hope) problem : how can I replace your custom event ‘DestroyProjectile’, and the ‘is valid’ node ? I’ve tried a few things but it doesn’t work. I’ve put what I tried below.

Do you think I should use custom events by creating variables next time ?