As Jim said, there's going to be a lot of personal preference involved here, heavily dependent on how you see your world setting developing, what types of civilizations exist in different places there, as well as how much time and effort you have available for designing and mapping it all.

Plus you're really asking two different, if related, questions - 1) the number of key buildings desirable for different types of settlement, and 2) what the appropriate size of different types of settlement can be for different types and numbers of special buildings.

The question of settlement sizes has come up on the Forum here before, and you might like to look over the comments on these two topics, both of which coincidentally came-up in late 2018:

Making a city with CC3+

Looking for advice on starting Village/Town/City size

There are also various systems for designing RPG settlements available online, some paid for (on sites such as DriveThru RPG), some not (such as blogs), as well as a number of random design systems, such as those on the Watabou site, although those provide primarily maps, rather than lists of the specific places you indicated as of interest.

Those should get you started at least, or perhaps help clarify what it is you want (or even don't want!) from such systems, from where you might feel more confident about creating your own settlement design system.

Good luck!

The original T1 Hommlet mapper was almost certainly David C Sutherland III (1949-2005) as the credits in the original module were "Art & Maps: Dave Trampier & Dave Sutherland". David A Trampier (1954-2014), a somewhat tragic figure from the Wikipedia biography, seems to have mostly prepared lots of artwork - such as the original "orange" cover for T1, and the cover for the 1978 "AD&D Player's Handbook", for instance, often prominently signing his work "DAT". Amongst numerous other items, David Sutherland though famously produced the isometric maps of the eponymous castle for the original Ravenloft module (1983), which seems a good fit for the isometric Welcome Wench plans to my eye at least!

Nice little shack!

It looks as if you may have a corner-join issue (SW corner). That could be because you started drawing the walls at the corner. If so, you might instead try starting partway along one of the flat sides, as if you start at a corner and then add a break in the wall - such as for the door - you can end up with this odd-looking effect otherwise.

And maybe add a window?

Looking at the symbol and terrain use here, I think these could be used to create an illusory city too, or a literal ghost town, perhaps with some additional colour overlay effects, and perhaps some transparency about the symbols (less sure about the latter point, however). Or indeed a city of glass.

Excellent! And now without the canvas roof? 😁 And then with the anti-aircraft guns mounted on the rear. And...

You know Forum folks - we ALWAYS want more symbols!