One of the things I've been considering is how to set it up. A simple hosting and whitelist seems the simple solution although I'm a bit wary of someone running amok. Although again a simple solution to that is to take frequent back-ups.
I'm aiming to tie up the back-end / non-server tasks by the end of January, both to establish what is being created with a clear end goal and to allow people to settle into their new year routines.
The architectural ergonomics will be decided by poll, whether there's a broad bias towards one particular style or whether each town is unique - regardless of the result of any poll though it'll likely always be excusable to have an outlier or exception crop-up somewhere, which likely will even add to the flavour of the map.
All the areas / ideas that have been mentioned / suggested have been considered - prior game maps have had each aspect they contain slotted into one of the listed upcoming polls.
@ComfyCapitalism - the aim is for the public to decide that. Each 'key' build will be decided by poll, although the runners-up will likely find a use somewhere.
Individual and unique houses are going to be wanted in bulk though if we're aiming for a truly large map, again something coming up in the next set of polls.