I'm no expert but I did make a house last year although the pieces of gingerbread were provided (it is an event run through my old high school blah blah). The main thing when constructing I found was to be liberal with the icing and make sure to hold it up in place until it sets, you can use toothpicks etc to help but I just found that a bit fiddly and not really worth the hassle. Just slather on heaaaaaaaps at every join and it should hold well, mine didn't collapse! Also a good idea to help it sit stable is to glue it with icing (again LOTS of icing) to a board or something so that the walls are really well supported. You can see pictures of the one I made on my Facebook (think it is in the Wall Photos album), I think it looks pretty neat

Mmm that house was so nice to eat too. I think I kept it about a week before I couldn't hold out any longer and demolished it within a couple of days. Not sure how long they keep though.