You could take half a year to do the place if you wanted to, there's no time constraints at all. Don't feel like you need to rush. But you don't have to do any building if you don't want to. The only rules are not to change the exterior wall shape, and in the case of any community lots to keep it the same type (coffee houses remain coffee houses).
Basically you could keep the layout the same if you wanted to and change all the decor inside, with new windows, flooring, furniture, etc. Or you could completely gut the interior and create a layout more to your liking, with whatever decor you want. Guess it depends on how ambitious you feel or what you have time for.
And I suppose a thread and poll would be fine to suggest and decide on the lot. There's definitely one from Strangetown I'd like to suggest.