well dont want to discourage you from trying it, I just never thought it would be worth the trouble to even attempt it, you are looking at alot of work putting plants in trees and maintaining them throughout the grow, just placing the plants where they would still get alot of sun seems difficult without removing some limbs or finding just the right tree.
would hold off on the insecticides until you know that you have a problem and need them hopefuly you wont need any.
as per fertilizers you might be able to go with an organic soil mix that would supply the plant with most of its nutrients for most of the grow.