-that feeding schedule isn't causing that outbreak, the guys feeding everyday, sometimes 2 times a day, yes. you got that one right.
-the only reason from this point on for more frequent than weekly water changes is if parameters change. because your tank is new (mine is 7mo old and I'm doing daily checks) you need to be checking parameters everyday, waiting for a spike, and if that happens before your weekly, then your day of the week changes. Once the tank settles down, getting that routine down is where the good tanks become great, it really is that simple.
-this may surprise you, but I might up your photo period. Monti if I'm not mistaken is high lightish, 7 hours won't cut it. those moonlights, depending on what you are calling moonlights, do jack diddly for the coral.
-at this point, just new tank syndrome, try to remove manually anything that's getting longer than the crabs will eat, and let it run its course. what is probably happening is the silicates/po4 that is in your new sand, and the rock is leeching, once the algae eats it up, your done.