Are you doing it with younger DCs? If you are, involve them only in the decorating part once you have built the house and the icing has dried!! Nothing worse than trying to commit a feat of gingerbread engineering with small children poking it and asking if it is dry yet every 30 seconds
I use caramel to stick it together. Sounds scarier than icing but sets quickly and very securely. Makes the whole assembly much quicker. Then DC just help with the icing.
If the pieces grow in the oven, you can trim them back to straight edges as soon as they come out of the oven.
Smashed boiled sweets make beautiful stained glass windows. I think you just put the sweets in for the last 5 mins or so but can't quite remember. But boiled sweets are surprisingly difficult to smash!