It is not clear from your drawing so the first thing I will ask is if you have separate supply and return piping?
From the photographs it appears that you may have Monoflo tees in a one-pipe system.
While it can be done, four zones in that small a house is likely not practical. The economic return for the capital costs involved will take decades to recover.
I do not like heat-actuated zone valves. They are prone to failure in my opinion. I do not know anything about the Taco EBV. If it is a true motor-driven valve it may be okay.
If you are not adding to the system then one circulator and the zone valves should work fine. Understand that if the circulator fails there will be no heat anywhere whereas if you use multiple circulators you can have heat in the zones that have an operating pump. If you do add additional circulator pumps be sure to install isolation valves or isolation flanges on each pump, including the original pump.
As shown on your drawing you have the circulators installed on the return side pumping into the boiler. If the expansion tank is connected to the boiler itself then you have a bad situation. The expansion tank should ALWAYS be connected on the suction side of the pumps. With multiple pumps this is usually best accomplished by having the pumps on the supply side.
I do not know anything about "wireless" thermostats. I like wires.