It's a pretty pattern and does look waaaaaaaaaay easier than the traditional garden. I'd say ... Go For It!
I started hand-piecing a traditional garden years ago. It comes out of the drawer for a few weeks at a time. Hopefully, it'll be finished before I croak and become an heirloom. If it isn't, I'm leaving instructions that they should just toss it into the ground with me so it won't plague my descendants instead of pleasing them. 8)
I also like your TO DO List. I'd suggest one change, though. Measure BEFORE you spend the money and do all that prep work.