Original chassis modification history questions

Hi All,
I've been reading a couple of books from my collection over the past couple of weeks, and have a couple of questions relating to the original chassis, and how they changed over time.

1)
It seems the ealry chassis fed cold air via ducts to the seats, which came out through the holes to cool the driver. It didn't work too well so they dispensed with them.
So where were the inlet ducts ?

2)
Alan Mann modified the suspension on his mk1 cars.
Did he move the mounting points, or just alter the arms and uprights ?

3)
Over time the cars seemed to have both engines and transmissions swapped about (especially the mk2s while testing auto boxes).
Were the mk1 and mk2 chassis the same, or were they modified / strengthened to fit the 427 engines and different gearboxes in ?

4)
Some cars were made as open topped chassis. Were these strengthened elsewhere to account for the lack of a roof ?

These just struck me as interesting modifications that don't seem to have been discussed before.
Anyone have any ideas on these ?

Cheers,
John.

John, as I understand it, and have seen it in diagrams, inside cabin air exited out through the holes in the seats and out the back to relieve pressure and make the cabin more flow-through.

That's not what both the books say though Mark.

They definitely say the early cars fed air to the seats to force cool air out of the holes, which would make more sense too.
I thought the vent on the roof (doesn't seem to be on all cars) was to let air out, along with the window vents...