heh, i'm always late to the party...
it's
cyano, the tank should be cycled within days, I think you can keep both fish, GSP will eventually be the only coral you have in the tank... it spreads way to fast and aggressively for a nano (this is personal experience with a 12 cube)... I think I touched base on all the questions!
Tank looks great
btw, I think you'll have a great lookign nano in a few months!