In response:

Plastic explosives and blow torches:
How do they get these items past the gate and increased security measures?

Cost not feasible:
Sacrificing a bit of space is a small price to pay to avoid the cost of another September 11.

Food during flight:
It's already been suggested that they have the food within the cockpit. This way there is no possibility of the food being poisoned. Also food served doesn't have to be exclusively hot. However, assuming the worst and the pilots are unconscious, the aircraft can be equipped to be flown remotely.