Long time no see, Cartographer's Guild!

So after a long hiatus from my map-making and game-making pursuits, I've been bitten by the campaign-bug and am knee deep in design of a town of 1000. I'd like to design this town as something fully fleshed out, that I can run numerous campaigns and one-shots in. I want to create a town that my players feel they can actively influence and see how it evolves as they play different storylines within it. Using services like the Medieval Demographics calculator and various D&D-related modifications of it (adding magic shops, calculating races and classes, etc), I've figured out the demographics of my city, and now I'm sitting here with my graph paper and mechanical pencils, ready to start sketching.

Here lies the issue... I've always had problems with scale, and this time I'm hit with the double whammy.

Problem #1: I don't know how many buildings I'll need. Sure, I can figure out the number of businesses easily, most of that has already been worked out... But when it comes to the homes of NPCs, I'm at a loss.

Problem #2: The size of the buildings. I have a very difficult time figuring "okay, this house should be about this wide" without drawing the internals, the rooms, furniture, etc, then calculating how large it was when I was finished.

I could probably sit down with scratch paper and a calculator and figure out on average how many houses there should be, with variables for larger and smaller families, and I'm sure I could diagram out a few 'sample' houses and buildings for size, but it seems like an awful lot of work, and I was curious if anyone has any tips or resources for figuring out something like that.