1)there should be some propane tanks around somewhere, and there should be a second floor. Strap 5 tanks together, open valves, attach handheld blowtorch on bottom and throw out of the second story window and wait for the fireworks. After my explosion went off, i'd duct tape aluminium siding on my arms, legs and neck, leaving my joints open for maneuverability. Put on goggles, the toughest pair of gloves I could find, make a makeshift shield out of metal, then grab a hatchet and go braveheart on their asses.
2)Have the police officer give me his baton and carry the little girl, with my frying pan and baton, I'd tell the police officer to haul ass to the safe house, while right behind them fending off zombies as much as possible(not worried about zombie bites considering i am immune, or else id be a zombie in the l4d world.) I would continue with the 2 unless the shit gets real, and I'd give the police officer the frying pan and tell him to continue on and save the little girl, yes very heroic aren't I?
3)Simple, cut back, pull my friend back up while cutting up the fastest zombies with my pistol and haul ass to the helicopter. Providing my friend isn't hurt of course.
EDIT 600th post!!