For electronic temperature control, I believe what you would need to do is convert from manual on/off valves to electronically controlled burners with standing pilots (on the HLT and MLT only). Most folks control the burner valves with LOVE (or similar) electronic controllers, either 110v or low voltage. The LOVE controller sends voltage to the gas valve whenever the temp falls below the setpoint you select, and shuts it off at the upper limit point. It uses a probe that you can either dunk into your brew vessel or mount using a bulkhead fitting. You need an individual controller for each vessel that you want to automate.
Check out this thread to see what I am talking about with regard to the automation piece.
https://www.homebrewtalk.com/f51/my-brew-rig-build-95433/ . Nicksteck had all the expertise already, being a HVAC contractor. The wiring looks more complicated than it is.
I assume you intend to mash in that uninsulated middle keg. I suspect that consistent heat control may be a challenge, and that you will be doing a lot of manually lighting the burner, running it for a short time, rechecking the temp, etc, repeatedly in order to maintain your target temp prior to mash-out. That might become tiresome. To deal with this, some folks insulate the MLT (it would be a shame to cover up that gorgeous stainless) or set something else up to maintain the temperature, either by a recirculation scheme or by automating the burner somehow.
Others with more knowledge than me will chime in here I suspect...my 3 tier "tree" is manual but I use a 10 gallon round cooler to mash in; with the lid on it holds the temp consistent for an hour no problem so I get to skip the whole heat management thing.
You have a single level setup so I dunno if you really need a sightglass on the HLT. Just use a little engraving tool and put some graduation marks on the inside of that keg. You can just look inside when you're filling it and use the marks to guide you. I made a little sightglass for mine because it is six feet up in the air, no way to see inside without a stool.
I'll post up some photos of the stuff you might want for electronic ignition, in case you are interested in going that route.