There's currently a wood retaining wall where we want to put the brick retaining wall, so it will probably involve adding a good depth crushed stone base & tie-ins to the hill. The wooden retainer has been slowly shifting. It's 4 stacked 1" x 8s", about 32" tall by 5.5'-6' wide. It may be necessary to dig into the bank a bit to line it up with the house. For the holes, we had an air conditioning unit moved, so there are several small holes, and there's one that's about 4-inches wide. There's 4" hole by the retaining wall & there's another on the side of the house where we had the vent for the water heater. The other holes are small, between 1/2" - 1." We are also considering creating a concrete patio under our deck. The area currently contains crushed marble chips. There's firewood stored there so we'd either need to move it or wait until another time. That area is approximately 15' x 25.'