I think this needs clEaring up
 

What would the half elves Dior, Earendil, Elrond and Elros have looked like. Would they have retained characteristics of both races? But what shape ears would they have? Would they have Elven ears and like when Elros chose mankind would they fall off or something? Or when Elrond chose Elvenkind would he have grown Elven ears as a sign of his chosen species??? I'm guessing that each manelf would grow more like his chosen race the older he got.

There's already a thread about this matter. Check this. :)

How pointy were Elrond's ears?

These might also interest you... You will find that Elves don't necessarily have pointy ears... Or then they do... Check.
Elves' Ears
pointed ears
Do Elves Have Pointed Ears? Pointy Elf Ears?

PS. The forum search is a useful tool... :)