After you've ensured the cycle is complete - unless you get established rock already cured, you can add inverts. Your cleaning crew. Snails, hermits, maybe a shrimp. But, you'll be able to ensure you've got consistent water with the ammonia being at zero, nitrates 10ppm or below (20 is acceptable for some).
Most coral you find will already be attached to small rock. You can use super glue believe it or not. There is also a silly putty type adhesive that any lfs
And you're right, good LR
will likely have stuff growing on it too, but look for pcs that give you ledges or slanted or horizontal "landing strips". An inch or two of landing strip space to affix smaller rocks with coral on it would work. Hopefully, I didn't confuse this too much.