They will buy them but I am fairly sure they do not sell them, I could be wrong as I do not have much to do with people.
There is no way to make more than one type of item at a time, unlike some vanilla crafting like threshing which can produced 5 or 6 items.. You can create recipes that produce something from nothing which is similar to creating two items at once, but it is exploitable and takes up another menu slot. I can send some examples if you want to see what I mean.
You can replicate something like a shelter with a new name and graphic and you can change graphics for other buildings but it seems that making a multi cell building is hardcoded for most actions to work.