If you use 75-100 lbs of live rock, then that should provide all the biofiltration you need. You don't need the cannister filters for additional biofiltration, but you can still use them without the media in them (bioballs, sponges, etc) to run chemical filtration like carbon, or other synthetic resins like Purigen, or phosphate removers.
Doesn't sound like you have a sump, so you're going to have to look for a hang-on-back (HOB
) skimmer. There are just as many good ones as bad ones, and it seems that the cheaper ones are normally the ones people curse about. That doesn't mean the expensive ones are automatically good... but just be aware that "you get what you pay for" kind of seems to ring true with skimmers... along with lighting.
Salt mix... all salt mixes are not the same, and whether one brand is "better" than the other is like talking about religion, politics, and the war in Iraq all at the same time! So I'll just say do some research (search here and other forums for "salt mix" or something like that) and you'll get a general feel for what salts people like and why. My advice is find a good name brand that is readily available, and stick with it. Don't hop from one salt to another in search of the "holy grail" of salts.