As long as that angel leaves a tiny little stub on the rock,they'll regrow.:D
But you never know.That Koran may never touch em.Plus you could try keeping a few sponges like the tree and ball sponges to give that Koran something besides corals to snack on.Most angels perfer sponge to coral anyhow.
The shrooms don't require intense lighting. And yes they will spread given the right environment. I purchased a fuzzy metallic shroom rock months ago and it's spreading like crazy. Atleast 4 new heads that i'm aware of.
I personally think shrooms are a great option for your first corals.