My Shield has two separate stats of block chance. Do they stack

The most important factor that comes from vitality is the +armor bonus%.

This becomes very prominent for melee fighters late game as monsters will start hitting you for really hurtful damage. So you would want to stack up all the armor you can. Note this % increase also affects elemental armor which is even more critical.

Let me give some numbers, in Act III you will be encountering monsters who hit for about 800 damage, while the armor you can afford to wear will be around 400. Even at that level 400 dmg will take out a good chunk off your health even at 40-50 levels. (These are approximate numbers, it may vary game to game) Imagine you have a nice 50% bonus on all armors cause of vitality. that makes your armor 600. which means you just reduced damage from 400 to 200. You will be able to hold your ground longer and take more hits.

Some of the champion mobs deal even bigger damages than those numbers, and may outright kill you when you least expect it.

Vitality also gives you block Chance if you are using a shield. As of update 1.13 the block chance cap has been upped from 50% to 75%. 500 points in VIT gives the character around 50% Block Chance. This might not be feasible but shield based builds will rely on VIT to provide those extra block chance to nullify damage they incur.

Hope that explains Vitality for you.

For gold:

• +_% amount of gold found means you get more gold when it drops, it doesn't affect gold drop rates.

For items:

• +_% magic finding means increased drop rate for gear, but not necessarily yields better gear. Each item tier (green, blue, yellow, purple) has its own drop rates (%), and it is this drop rate that will be increased.