Quick question: When a vehicle is KO'd, the super heavy object left is the vehicle figure disattached from the base; or is it the entire base?

I have a doubt with the size of wrecked vehicles. So far, I have considered the cruiser and the motorcycle to be 1x3 and 1x2 squares respectively. In the case of the Batwing, I treat its wings as part of the object, allowing me to pick the up from far away. Is this correct?

Also, I need to know if the bonus of the Book of the Skull by equipped hammers counts the figures with a hammer which has been KO'd during that game?

When a vehicle is wrecked, the ultra heavy object is the same size as the base.

Yes, the BoS is only checking how many hammers were equipped, not how many hammers are equipped.

Since it seems the OP didn't really search I will ask, are you aware of the difference between equipped and assigned?

Actually, no.

The book will not count those hammers that are picked up (assigned) as normal relics, only those given (equipped) as described in the portion of the book "Equipping a character". It must be the character that the hammer is dropped on at the time of dropping. You can't move off then come back or wait til next turn, it must be done in the order described in that section. So if you have 3 equipped and 1 that picked up a hammer like a normal relic this will not count as 4 equipped.