I thought I already answered this. You're doing a good thing with using sch 40 PVC between the RPZ and the manifold. None of the pressures you have listed present a threat to the sprinkler system.
Master valves (two of them) should work with your Rachio controller, which lists an output current capability of 1.3 amps. Nearly any common electric valve you could choose nowadays will have a solenoid with an inrush current of 0.4 amps or less, so two master valves and one zone valve being activated simultaneously gets you a top inrush current of 1.2 amps or less.
With the plumbing you intend to install, the master valve(s) would no longer be about protecting plumbing so much as being insurance against a stuck-open zone valve. If it happens your zone valves have flow controls, you can increase their reliability by partially closing the flow controls.
I have completed all the work yesterday, it was not easy

Because of the way the house is, I basically had to run a conduit from front yard's master valve to the garage, route the cable from garage through the basement, and run another conduit outside to the backyard where the backyard's master valve is. Then join them together, and run one master valve wire through the main conduit that carries all other sprinkler wires to the office, back inside the house. Installing PVC was honestly the easy bit, probably an hour or so between cutting, measuring, gluing, etc. Drilling the concrete walls that are 12" thick, and doing it twice

, and routing all the cable (and even had to do a junction box because the cable wasnt long enough) took about 10 hours.
So far so good, no leaks, yes Rachio can handle 2 master valves and a zone valve and everything seems to be working. Thanks so much for your advice.
The only thing that I have left (besides adding more zones) about this system is the flow control. My main goal is to know when there is a leak, any leak, throughout the system after the master valves. Ideally I'd like to know the leaks before the master valves (copper stuff) but the 1" copper pipe leaking is such a low probability.
The problem is all these flow control devices they sell like hunter flow clik really address the problem of a particular zone spending more water than it needs and it does that by asking you the GPM on a zone and if it sees GPM higher than that it shuts it off. The issue is my zones are all maxed out GPM wise. I have 11 GPM measured and I m squeezing every bit out of it from each zone. So that feature would probably never work for me.
Also the scariest leaks are not the ones when sprinkler system is running, its the ones that happen out of the blue as a major rapture in the middle of the night when you are sleeping (or when you are on vacation) and they happen before the master valve on the line thats under constant pressure. Those are the ones I want to be able to detect/prevent.
It seems like the only thing that will help me with this is those remote controlled water meter/valves they sell which are not really for sprinklers but for the house. There is a few but I m not sure which one to go with.