I've got an electric mixer, from Lowe's. I use it for concrete, not mortar. We've never been happy with the consistency of the mortar produced by a mixer.....always too wet which then makes a mess and causes stones to slide/float. It sticks in the back and doesn't turn loose unless you keep adding water........its just doesn't mix well. I don't know how ya'll mix it but we use a hoe in a wheel barrow + good posture.......really not difficult. We exchange mixing and everything runs smoothly. If the mixer would work, I'd use it.
The island, within the walkway, does come to a point. The opinion of the homeowners has changed and we'll be pouring in a couple bags of concrete to make it into a tight curve.
Thanks for the comments, hopefully more pics soon.