Well I think when you meet someone known after two years you must want to know what happen to them.May be luffy didn't pay any attention but others do.So do you think
I think it's normal for a pirate to lose his eye. Besides they never asked each other about their 2 years training at all so an eye wouldn't really be that significant unless of course oda decides to do some bullshit with his eye that somehow gives him power or something.
One cannot simply train with Mihawk and not loose anything
Mohawks sword is longer than Mandingo's ****, I bet he slashed zoro's eye during training. He's ruthless