I think you're out of luck on both counts unfortunately. Multi-calendar works great for differing year-ends (switching from 12/31 to 3/31 for instance), but it still uses the same periods for both calendars, they're just arranged differently. 4-4-5 versus a calendar month would require the periods themselves to have different start and end dates, and I don't believe that's allowed. Also, as far as I'm aware you can't use multibook that way since the calendar setting is set on the subsidiary record, independent of book. The best you could do (if you can solve the calendar issue above) is to just toggle that setting back and forth between running reports, which isn't very efficient obviously.