Is my design for this drain-waste-vent system acceptable?
Every code authority is different. From what I was told when remodeling my house over the last 3 years, is that draining appliances on the same walls can share a vent. Each wall would need a vent. Same drain line is fine, but the vent needs to be within a certain distance of the appliance. I have 1 2" vent that my kitchen and bathroom use, on the same wall. My washer has its own, and my second bathroom has its own.