I would imagine that very long eared rabbits can hear slightly less as the ears usually fall over restricting the free passage of sound waves. The carrot improving sight thing is a myth, it was spread around during the war to put the Germans off finding out about the radar that we had invented.
As they don't hear with the actual outside bit of the ear I can't see how it would make any difference. They hear with the inner part of the ear.
Although they contain lots of vitamins, there is nothing in them that would help eyesight, although most animals see better than humans in the dark anyway.
Lankeela, whilst they don't actually hear with the outside, the ears are there to catch the sound-waves, or else we would just have holes in our head instead of protruding ears!! the larger the ears protrude the more likely they are to catch these sound waves, until they fall over and restrict the entrance to the ear.
Why don't birds have protruding ears I hear you asking with my protruding ears? No idea!!!