I have two bows, ebony and elven. Ebony does a bit more damage, but is it considered a "heavy" wep since ebony is heavy armor?

Loading screen says something like "heavy armor and weapons slow you down more" so doex that mean using ebony bows causes noise when sneaking? Or no?

No. Its a weapon not armor. Only armor is split between light and heavy. Weapons are 1h/2h/Bow. Weapons speed is the factor your thinking of, and that has no bearing on the noise level.

the real question is do two handed weapons have a sneak kill animation?