It would have come with a hard plastic buttplate with the word 'BROWNING' on it.
No.
200, 225, 250
Browning BlR
If ordered that way
No, never. Browning did however install them at their shop in St Louis if the customer wanted to order the gun that way.
Only Browning knows. My guess is that the 308 is easy to fine tune with loads without it.
1987
Please check the link below for Browning Operations Manuals. Choose the Manual that matches the model of your gun. Instructions there will tell you how to disassemble.
7mm Magnum and 300 Winchester Magnum
No, never. Browning did not make any recoil pads standard on any A5 except the Mag12. For an extra fee, Browning would install it for you at their shops in the US, but it is not factory and was not imported from Belgium with a pad.
Yes and no... Browning used to offer the .308 with the BOSS but not anymore. You might be able to find one in new or excellent condition somewhere, if you're patient.