I think you should submit your question about maintenance to a another forum that is geared toward that. (Check the master list by clicking on "Garden Forums" above.) Then AFTER you get things cut and cleaned up, take a new set of pictures (with better lighting) and start a new thread about your project. (why does this look like it might be a parking lot?)

I suggest you find the identity of those trees. Then prune according to their species. There is a Name That Plant forum on GW.

As to the fallen leaves, you will need a rake and a broom. I do some of it with my hands. (Or hire someone) The way to remove dead plants is with a shovel. Water the area ahead of time so the soil is easier to dig. If there is a stump that is too difficult to remove just leave it. Time will take care of it.

You have so much vacant concrete. It would be nice if you had patio furniture or really anything to make it less oppressive.

It would help if we knew your USDA zone and location. If you are in California we have our own forum.