Maya animation Alembic Cache to Unreal.

I think that you have to split your maya character in 3 different animations:
hair-body-cloth.
export cloth as alembic
export body as fbx with anim
but concerning the hair …exporting as alembic will be a huge file and I think you have to look at the Unreal Engine Livestream - Exploring Digital Humans - they explain how they handled the hair.