The standard for house ventilation systems is:
- Fresh air goes into "clean" rooms (bedroom, livingroom),
- Used air gets sucked out of "dirty" rooms (bathroom, kitchen).
Since the "dirty" rooms are getting their air from the rest of the house, in many circumstances those rooms don't even need their own heating/cooling.
As for air flow, I believe the minimum is 0.5 house volumes per hour, the maximum is either 2 or 4 house volumes per hour (don't remember). When replacing more than 2 (or 4) house volumes per hour the heating/cooling/recovery system may not be able to keep up, leading to noticeable drafts and energy loss. Also, the ducts should be sized to keep air speed below 5 m/s to keep noise down.