Very Cool project. I'd be tempted to try that with a 4x5 removable back.
"Spec'ing it out, rounds of prototypes, proof of concept" isn't lego vernacular sorry. You sit down with a pile of legos, visualize something and build it, changing it as needed while building it. And if it's not ideal, you build it better.
Sounds like he's taking work home with him or something.
I have always used Lego as the plural e.g. 'a box full of Lego'. Is it an English - American thing? Or perhaps just one of those oddities like fish and chicken which could be singular or plural or fishes and chickens could be used instead.
The word which doesn't look right which I see on forums occasionally is advices. A plural form of advice? Just looks wrong to me!