I know that the max gain comes from 252 EVs, but can you still go over in X and Y? The reason I'm asking this is cuz I maxed out my Hitmonlee's attack, used a reset bag later, but it only said -252 in attack.
Yes a individual stat now maxes out at 252 EV's instead of 255 EV's as of Pokémon X and Y.
Yes, they are. I identically used a 1-EV bag on one of my Pokemon, and when the limit was reached, it rounded up to 252.