When you order the gravel for your parking area, be sure to specify "road base". It is a mixture of gravel and lime fines that packs solid and stays on top much better. It can compact to look almost like concrete, and will make an excellent base if you pave later. If you get loose (washed) gravel, it will end up everywhere and does not compact. Using roadbase, you can omit sand and probably the weed barrier cloth.
Your ideas look real solid, although I have never used barrier cloth under gravel before. I don't see what it could hurt though. Usually have cleared and compacted drive/parking area with a dozer or blade then applied road base. The slight excavation removes enough topsoil that the base is more solid, and gravel stays put. In your case, just be sure to excavate enough around any sidewalks and curbs that the gravel is about 4" deep next to it and is level to the concrete (if any). Using landscape timbers, you won't need to excavate, they should contain the drive. You might consider those retaining wall concrete blocks as a retainer also, or form your own concrete curbs.