Medieval towns usually grew around a marketplace, and a wall was built around it as soon as possible, ie. when the town was big and wealthy enough. After this, all the buildings tended to be built inside the city walls because it was safer there. If your town has walls, you might get away with just drawing the "roofs" and to leaving the amount of stories ambiguous on the map. Alas, a town of 1000 inhabitants might not have walls if it resided on a fairly peaceful region. But if your town was on restless region small walls wouldn't be at all unrealistic almost on the contrary.
If you are going to the full length, I'dd suggest doing three mock-up buildings, one for poor, other for middle class and the third for the wealthy. Or you could do one house, and just fill it with three families from the three different stratas. For example, poor family would have an apartment the size of a middle class living room, and a middle class apartment would the size of a wealty family's livingroom. You might want to adjust that according to your world's customs. According to the "Town" by Lisa Steele, a poor artisan might have an apartment only 4x4 meters in size!
Most of medieval townhouses were residential homes, and they usually had a shop on the street level as towns were the centers of commerce. They usually faced the mainstreets to near the customers. This made the houses often really narrow on the streetside but stretch long inwards.
I don't know if this helped at all, but I suggest you try to keep things simple and go to detail work only when you need to, ie. when your players come around