Remodeling, the gift that keeps giving. Every task creates other tasks and on it goes. Glad you have not had any major train wrecks thus far. Will the fill where you back out of the garage need a retaining wall or do you think you can manage it? It appears in the photo that the supporting slope behind it is marginal at the least. Perhaps its just how I'm looking at it. If you are already near the drip line of those two trees with the fill, a reatainig wall may be your only choice. Adding dirt inside the drip line of the trees is a BAD idea.