Others will answer with more detailed information.

I have Warmwire by Suntouch installed in my new bath. I did it myself and the electrician wired it for 240, the Warmwire product is selected for either 110 or 240. Electrician said that 240 was better, I think it warms up faster. All should warm up to what ever temp you set it at.
Wires installed:
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then with the plastic lathe I used over the wires:
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SLC being poured:
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With regard to the shower pan, I was told that I could place my tub onto the underlayment before the SLC. But I wanted the tub to be on top of the SLC so that is what I did. I did not run my wires under the tub, and kept 6 or 8" away from the toilet cutout.

What are RPM mats?

I notice that you do not have a de-coupleing membrane in your plan. Ditra is one. It allows a bit of horizontal movement to happen without cracking the tile. It is set on top of the SLC with thinset, then the tile is set with thinset.

I really like your idea for plastic lathe. Less chance to break the wire :-)

RPM mat is an alternative to backerboard with built-in grid for heat wire installation. From what I've read it simplifies whole floor / wires installation significantly. Even though it's more expensive than backerboard (about $14 per 20"x44"), I think the higher price is justified. Plus the room is small, so we don't need a lot.

As for Ditra, we haven't decided yet whether we will put it in though we have plenty left from kitchen tile installation. I'm afraid it will raise the floor more than we can allow it. I also read somewhere that having Ditra between wires and tiles results in slower tile warming up and temperature doesn't get as high as without Ditra. Thus the hesitation.

Here is a link that might be useful: RPM mats

Those mats look nice. On my installation I put the lathe on top of the wires. I was careful and there was no wire breakage. The lathe is to add strength to the SLC sort of like how when concrete is poured it is re-enforced with screen or re-bar.