i am building a retaining wall for a flower bed 30 inches high i a few feet in front of my porch. My porch concrete foundation stands about 33 inches high above the ground and I will be back filling dirt up against my concrete porch foundation to level it out.

1) Is it neccessary to have some sort of barrier between the dirt and the concrete porch foundation to keep any moisture away from it? Or can i just backfill the dirt against the porch foundation?

2) i will have a french drain along the retaining wall. Is it also neccesary to have a french drain in the back against the porch foundation walll?