Do you have any unions in your steel lines? In case you have to tighten some fittings down the line?
Might want to use a strap in the middle of your long water piping, too, quite a bit of weight there.
Nice thing about the zone controller, it can be configured to simply make a TT signal to the boiler- essentially acts like a thermostat.
That means if you do go without it to start, using just a Tstat, it will slip right in there later.
The power distribution to the zones is really convenient and neat wiring. One power line in, each zone goes out.
BTW, I strongly recommend all your wiring be done with armored cable. Not only is it attractive and neat, it passes all the code requirements.
Yes, get the cutting tool, it makes all the difference
Keep going, almost there!