It really doesn't matter if you go with a 520 or 530, either will work as long as you get the sprockets to match. If you want longevity, go with the 530 because it will stretch less and last longer over time. The 116 should be the number of links in the chain. So if you were to get a chain, you would want 120 link chain, and you'll cut 4 links off when you install the chain (most chains come in 10 link increments, 100, 110 or 120 links). Driven and AFAM are good sprocket makers, i would stay away from vortex. Vortex has its niche, and longevity tends to not be it. As far as the chain goes, its up to how much money you wanna spend. Definately get an O-ring at the minimum. If you wanna spend the extra money, get the X ring. Either one will work fine.