I wouldn't count on the single bright being bright enough for any coral, a friend tried a double bright and failed miserably. I'd also look into smaller equipment then the MJ it'll take up a lot of real estate inside a 7.5 go small like a koralia nano or tunze nanobelle. Not sure why you're looking to do both a the maxi jet and a powerhead?
Also filterwise I'd look at an AquaClear50, a bit more roomy, more versatile and cheaper for media, never used a biowheel filter on SW but I imagine saltcreep could lock the wheel up quickly.