Wall hole components is new to me, but I'll take a look and I still need to get my head around proper setup of symbols. I'm just glad that there's a way even if it might take some playing around to get to it!
As for the construction, it will be a wood based backing board before applying lime render, so as you say it will very much be hand sculpted. I want to go for soft, broken edges, but not too far or it becomes a bit 'funhouse mirror'!
I have lots to learn still!