Some character stats seem meaningless?

Lokai

So when you go into a given characters stat screen you will see some stats like critical strike chance that is measured in 100's I've got some as high as almost 400. this number is meaningless to me

it also begs the question is armor a straight subtraction from damage or is it another number that isn't going to correlate in a direct manner?

and then if I get a 50% crit buff is that a straight buff or buffing the characters critical strike stat? meaning is it my chance to crit =50%+critical strike stat OR critical strike rating x 1.5?