Going with the idea of the combination map, there is a good amount of ground to cover in terms of climate. I have not incorporated any cold/hot weather gear into your packs so I'd imagine where we begin is temperate and mild given that you've had to travel there. We can run the gamut of climates on the map if people want to have come from a place that is cold or have a desert area in the map. I'd like people to be able to put their own stamp on things in terms of what local areas are like and geographical features that exist. For now, I'll just say anything is open for discussion as we populate the map.
In terms of distance, I want to keep travel times and distances loose. Since you are going to have to travel around to deal with each impossible quest (I don't imagine they'll all focus on the same place) I don't want to get bogged down in miles and meters and such. In general, I'd expect the group to travel at the speed of plot. Character abilities that focus on speeding or easing the difficulty of travel will, of course, apply to making your voyages easier.