Well, Mark's already defined the "remotes". They are usually (always?) in pairs and a tractor may have only one, or may have more than one pair. Of course a pair is required for the double acting cylinders, like Mark said, but some implements may only use one, like my neighbor's haybine (hay cutter). The cutting is powered by the PTO, but a single hydraulic line raises it for transport or to get over small stumps, etc. The single acting cylinder is all that's required to raise it, and the weight of the implement itself will lower it.
As for what combination of tractor and loader is best; there are too many different ones, the question is too broad for me. Can you be more specific? Or tell us what you want to do with it? Personally, I prefer to stay with the same brand of tractor and loader instead of putting an aftermarket loader on a tractor; however, there are certainly some good aftermarket loaders available.
Bird