Bit of a tangent, but I'll roll with it for now (If you want to continue the conversation though, please head over to the Missions sub-forum).
1) Missions generally take place in locations that are currently "unused". This gives us free reign to meddle with the location, and we don't have to worry about main metaplot screwing up the Missions storylines. So doubtful we'll visit Boston anytime soon.
2) It was decided to break Missions down into shorter storyarc "chunks" and to define those better. Since Season 4 bounced between two different plots, it was confusing if players were only interested in one plotline. Season 5 is a little more linear, but we decided to keep things contained in 6-episode arcs. These arcs all link to form one bigger story, however. So initially, we were labelling them A, B, etc. So you would have SRM 5A-01, 5A-02, etc. Then SRM 5B-01. The plan is to do 4 story arcs for the full "Season", so it would have culminated with SRM 5D-06 being the final adventure. The Powers That Be decided this was potentially confusing (and it apparently messed with our contracts and our book numbering system), so the decision came down to break each arc into a different number instead. So arc one is SRM 05-01 through 05-06. Arc two is SRM 06-01 through 06-06. So to designate the actual season, we now just use the location name. So this season is "Shadowrun Missions: Chicago" instead of "Season 5".