Thanks for taking time and effort to answer Ifixplanes. Are the diagrams you have in the public domain?
In the smoke removal configuration air from the electronics bay is dumped instead of being diffused to the lining of the forward cargo hold. This allows an increased ventilation rate through the cabin whilst stopping air from circulating to the forward cargo hold.
The two bottles should give three and a quarter hours of fire suppression in a hold to cover 180min ETOPS (in NG).
This is my interpretation of Boeing Vol 2 (the only info I have).