Jammer scoring whilst down: I think this was posted already, but 8.3.1 mentions three things: Pass opposing skaters (1) in bounds, (2) legally, (3) without committing penalties. The question is, is a downed jammer in bounds (yes), passing opponents legally (I'm not sure?), committing penalties (No, providing she doesn't hit anyone whilst down).
You must be upright to be in play. This is in the rules. Downed skaters are not in play, until they are standing, stepping and/or skating. From definitions:
Down
Skaters are considered down if they have fallen, been knocked to the ground or
have taken a knee. Skaters on one knee are considered down. After downing
herself or falling, a skater is considered down until she is standing, stepping,
and/or skating. Stationary standing players are not considered down.
In Play
When a skater is positioned within the Engagement Zone and is in bounds, she is
in play and may legally block and assist. Downed players are not in play.Jammers may engage each other anywhere inside the track boundaries for the
duration of the jam, but must be within the Engagement Zone in order to legally
initiate engagement with Blockers.