B757-200 Captain relates multiple shortcomings in the preparation for and conduct of an ETOPS flight.

Narrative

Weather forecast called for scattered thunderstorms in the evening. I requested a relief pilot at XA00 local while driving to the airport and my request was denied by scheduling. Dispatched with APU inop. Aircraft was at gate for approx 5 hours with inadequate air conditioning. When we arrived at the gate 1+10 prior to departure; the cabin was extremely warm and stuffy (approx 95 degrees F). We requested an alternate source of pre-conditioned ground air which turned out to be an external air cart which only supplied air for the packs for about 10 minutes before quitting (insufficient time to cool the cabin). I advised the gate agent to hold off boarding until the cabin was sufficiently cooled and ventilated. Another air cart was delivered; which also quit after a few minutes. Finally; a pre-conditioned ground air conditioning cart was located which was adequate for the cooling needed. We got off the gate about 45 minutes late just as the evening thunderstorms started to percolate. We were forced to run both engines for adequate cooling on the taxi out and were confronted with a lengthy ground delay due to the departure fix being shut down. We advised Dispatch that we would most likely not have the required fuel on board for take-off and to get a relief pilot on the way. Needless to say; the ACARS was now flooded with suggestions to reduce holding fuel (even in light of a re-route which would add 100 SM to the original filed route). In addition; Dispatch put pressure on us to go without a relief pilot because it did not fit the 'guidelines' which the company now dictates. I guess there is no longer any reliance upon the Captain's judgment and experience! We elected to return to the gate upon reaching minimum takeoff fuel as there was no chance of being cleared for takeoff in the next 20-30 minutes. A relief pilot was called out and we departed 2hrs+06 minutes after we returned to the gate. After we returned to the gate ground air conditioning was inadequate for the completely full cabin. We were faced with many irritated; hot; hungry; and thirsty passengers who were asking to go into the terminal for respite. I agreed and asked the passenger agent to intervene. He procrastinated to the point where I ordered him to get all passengers off immediately; in no uncertain terms. After re-boarding I learned that our Senior VP of Maintenance was on board. I politely asked him to come up to the cockpit to discuss the events that led up to this extensive delay. I pointed out that it is not a good idea to have ETOPS aircraft crossing the North Atlantic at night with an inop APU. Secondly; I suggested that if the APU inop operation is undertaken; then it is incumbent upon management to provide the highest level of support in order to preclude the fiasco that just occurred. He promised me that the calls to the appropriate people would be made to correct the situation. I was very disappointed that he did not take a proactive role in assisting the crew from the outset. Upon researching the logbook; it is evident that the APU has been on and off MEL for four days. Somehow the previous logbook (prior to 4 days ago) is missing from the aircraft. I suspect that the APU history is much longer than the flight crew has the ability to ascertain from the logbook. This event occurred; I believe; as a direct result of the failure of command and control by management. My crew was exposed to several latent hazards before we even arrived at the aircraft. Upon assumption of our duties in the cockpit; we were starting out 'in the yellow' due to the extreme temperatures and poor ventilation Then the active hazards created by the weather and circadian factors kick in and the next thing you know you have yellow approaching red. Experience and judgment dictated a return to the gate for more fuel and a relief pilot. Dispatch should have recognized the diminution of active barriers in this operation and should have assisted theCaptain in his initial request; rather than further exacerbate the latent management failures by suggesting that a relief pilot was not 'required according to company guidelines'. Furthermore; the Senior VP of Maintenance should have taken an active role earlier in the flight to help the crew mitigate the situation. His promise to fix the problem obviously was never successfully carried out as evidenced by the logbook history.