Where you are going in Miami Lakes, you can take the Crawlmetto over to 95, go north a little to 595, scoot over to US1, go north to SE17th Street, hop over the bridge and dive with American Dream out of the Pier 66 marina.
Dive shop-wise, lots of guys down in Miami make the trek to Fill Express off Copans Road (I95 exit - head east to Dixie Highway then south a little) even though there are many other dive shops much closer.
Tarpoon never did much to thrill me; H20 sold their boat - but feel free to check them out. Some people may recommend Brownies up there off SE17th Street - this is a shop that also leaves me a little less than enthused.
You may love all three of these operations and find Fill Express to be akin to visiting the dentist - visit them all and make up your own mind. Everyone has a website now, so do a little research, planing and travel and have a great time.
You will like American Dream though.
Oh, and leave the cheesehead hat at home.