Very kool build! I like using what you got and your ideas should make a pretty functional vertical. I also really like those 1/2 split firebricks, used them to line my firebox and they work great.
The first smoker I remember having was an old porcelain steel insulated fridge with a charcoal habatchi in the bottom, very small fire and vent holes in the top & bottom courtesy of a sledge & big screwdriver, just kept punching holes until we got it working. Made some good mullet & mackerel with that one!
Got a bunch of cooking toys and a custom metal fabrication shop where I spend my time building all sorts of smokers & outdoor cooking gear.