Some people may disparage Yamaha, but they've always built solid, dependable gear, and your receiver should drive the 602s without difficulty. (I'm assuming you aren't trying to fill an arena with rock concert-level sound.) The soundstage will be as good as your speaker/room combination will allow. The Yamaha will not be the constraining factor here.
As for the speakers, it depends on which monitors you mean, but both B&W and Paradigm have good reputations. One is not better than the other, and you should to listen to both and decide which YOU prefer.
As for the speakers, it depends on which monitors you mean, but both B&W and Paradigm have good reputations. One is not better than the other, and you should to listen to both and decide which YOU prefer.