So, the Grav-Weapon Conundrum

[Etched Oracle]

I'm sure most of you have seen but just to cover it, the rule on Grav-weapons is as follows:

"When resolving a hit against a vehicle, roll a D6 for each hit instead of rolling for armour penetration as normal. On a 1-5 nothing happens, but on a 6, the target suffers an Immobilized result and loses a single Hull Point."

So the big questions are:

1. Does this negate a vehicle's Cover save?
2. Would 2 hits due to Salvo cause 3HP loss?

I'm bringing this up as I will no doubt be fielding a gun or 2 in my games and I want to ensure there are no arguements midgame by instating a 'Club Rule' until this is FAQ'd. I have no preference over with interpretation of the rules is used, so long as everyone knows and is aware of it.

For what its worth I believe it does negate the Cover save as its bypassing the Glance/Pen step, but that 2 shots would result in 2HP loss not 3 as the shots are resolved simulataneously, so the vehicle wouldn't be Immobilised at the time for either shot as they resolve together.