Good choice. My son has just done exactly that, with the same size tank. He lucked out I had a spare skimmer for him, the skimmer is important you are best to get a good one, likely around a thousand dollars or so ( Salt tanks aint cheap).
Don't use the cannister or the air pumps. Salt's a bit different the filtration is done by bacteria that live in the rock. You get special coral rock that is porous for the bacteria to live in, it is referred to as "live rock" due to it's population of bacteria, and eventually, hopefully, the many other things that will grow on it.
But the biggy to think on here is money, even though you may have a lot of gear already, you will be likely to spend 2 grand or more to set up. All newbies including myself like to think they are just a little smarter and can do it cheaper than the rest, but eventually to do it properly, some big bucks must be spent.
EDIT - Sorry misnoma I wrote this before seeing your post, covered some of the same ground