I like to trench out the walkway or dig down to get rid of some dirt. Then I apply the weed screen, then back fill sand, water, then sand. Then I figure the height of the earth and make sure my rocks are that level.
On the borders, I like the rigid metal landscape interlocking strips. They will hold in the rock and cement and keep that together and also keep out adjacent grass. Its also easy to weed eat on the outsides.
Now, the sand foundation is the cheap route and will have some dis advantages with season and climate changes. The rocks will heave and fall with the seasons.
You can forgoe the sand and lay down a good 4 to 5 inch concrete slab and place the rocks on the wet cement and press downward for a nice stable walkway.
Really depends on your budget.
Concrete method is expensive, the sand method is cheaper and easier.