As you can see... Lots of differing methods to get to the same place
For a 15 gallon, a pair of clowns would be about it, IMHO. (And not my choice, if I were starting a 15g tank. But that's only me, I don't really like Clowns) Are you going to quarantine, or buy pre-QT'ed?
As to CUC, until you have algae (AND IT WILL COME!) all you have is left over fish food. A 3 or 4 Nassarius snails will clean that up. As you get more algae, add the grazers.
You can add easy coral really any time, but it doesn't hurt to let everything settle. You are in for the long game. Don't get discouraged about the 'ugly stage' happening. It can last a few months, a year, it's natural and a process and needs to happen.