For cleaning that trunk, try a soft bristle toothbrush and water. That green should come off pretty easily.
As far as the foliage goes, allow some leaves to remain on everything you want to be green. The farther out on the branch that leaves remain, the farther out new growth may appear.
Your tree looks pretty typical in that they have very dense canopies which prevent a lot of sun from getting down inside, near the trunk. Selectively removing single leaves can retain the general shape of the tree while letting some light in.
Take plenty of before and after pics, and show us!