my preferences:

A) Scenario
A.1 Era: Middle to end of the middle age with castle, cathedral (or something similar), caravel...
A.2 Magic Setting: I like the idea of GspRooster: magic is everywhere in a more or less scarce quantity but only few people really know how to use it. A part of the population can learn simple magic trick with effort and training and it's considered an achievement for the untrained. Those that specialize in magic often beging training in their childhood. By the time they grow up, they become much better than the average folk they are still level 1 mage; so no fireballs. Others more lucky, but far less numerous recieved the gift of magic at birth. They don't have to learn it but they still have to master their power.

So the way I see it:
50-70 % of the population can't do magic at all, even with basic spells with scorlls or whatever. ( dnd: they don't have ''use magical device'') It can also be because they don't know how to read or because they don't have the money for it.
15-30 % can do 1 or 2 little magic tricks often with the help of items
around 10% of people can do magic on a more or less daily basis, they are not all magicians but they have potential

those that received a gift would be less than 1 % of the population but these people have more chance to become proficient with magic.
Thta was the question of magic potential but some have more talent/ trains more than other. The less powerful the spell, the more mages will know how to use it.

A.3 Major driving forces / Uncommon effects / Themes:
B) Physical Characteristics :
B.1 multi-continental
B.2 pretty much like Earth. I would like to have a binary star system, even if it's just in order to have a very bright star in the sky at night and even during the day. it might even be brighter than our actual Moon. So the planet would orbit around the star at 149m km and another but smaller star (maybe a red dwarf but the difference in mass does not need to be important. If the difference is small the two suns might need to be further apart to avoid shattering the planets orbit) would orbit around the same star at billions of km.

C) Technical Details
C.1 and 2: I can map too ! Use an easy way to divide the map such as squared plots, possibly with buffers (I haven't made up my mind about this point yet). People should be ree to decide what area they want to map.