The shed idea works great with the side walls doubling as a roof when you have them in the "up" position. You can do more than adequate woodworking with the tools you selected. I would purchase a "track saw" in addition to replace the circular saw you mention. A track saw is primarily a circular saw that rides on a track so you get straight cuts. It's also invaluable for cutting down large items such as plywood. That said, I would own both a track saw and a miter saw.
Since your budget is tight, you might consider purchasing used tools. Many of us do that.