Hi, A.J. It looks great, but I think you're overthinking it! Having clay soil does not mean you have to go to heroic efforts to bring in soil from elsewhere. I have very heavy clay here in Emporia, Kansas, and I find sheet mulching (with no additional soil) is very good for bringing soil life in to boost the organic matter and loosen the heavy soil. If you have standing water, just dig some clay from one spot and pile it on another -- the elevated clay will drain and weather into soil in a few weeks.
But my favorite technique is to add a layer of clay (from a spot where it's unwanted) on top of every layer of greens & browns in the
compost pile... it inoculates the pile with soil life to speed decomposition, holds water in the pile so it doesn't dry out as quickly, and when the pile is decomposed -- without turning! -- the compost is already mixed with soil and ready to use.
Another way to water the bed efficiently from a rain barrel would be a soaker hose (recycled rubber) underneath the mulch. It doesn't deliver the water directly deep into the soil like the buried flowerpots, but if you let it drain a whole rain barrel at a time, the water will soak quite deep. I've had great success with this approach.
I'm not sure what you mean by using the path for water.