Another mounted INF clarification appears to be necessary.
5.11.2 ...If the vehicle + infantry combination is fired on, the attacker makes one die roll for each attack on the combination, but calculates the odds separately for the vehicle and all the infantry and applies the results separately.
One thing that is missing (in the errata or the FAQ) is whether or not the INF that's mounted gets terrain bonuses for defense.
It's arguable that INF defensive bonus comes from their ability to scatter; INF on a tank can't scatter, so they should not get a bonus from the terrain.
However, it's also arguable (and from a KISS perspective, easier) that terrain defensive bonuses should apply in all cases, regardless if the INF is mounted or not.
I can honestly say I'm divided on which way to go with this.