On SOME Fords, not all, the chassis serial was stamped when the engine was installed and is in fact the engine number which is a curious way to do things. There is usually also a vehicle serial on the data plate but this isn't stamped into the chassis.
This is where to look: adjacent to the engine mount on top of the right-hand chassis rail:
Olive drab blue?
Yes, there should be primer as the base coat, then khaki No2, then another colour if it served in a different arm.
Yes, if you have the ARN you can visit the AWM and go through the vehicle record books. This won't tell you a lot about the vehicle, just the basics of when acquired, perhaps engine changes, and date of disposal and where disposed. For example many Fords were disposed of back to Ford Motor Co to e be sold through the dealer network.
Good luck with the pictures - the instructions in the read me should help.