On Crossbows: Try pulling an 80 pound crossbow back and then knock a bolt, without making a fuss and blowing your cover. The crossbow found widespread use because anyone could pick it up and use it. It was just as effective against armor as not. And the wounds were ridiculous. Pope Innocent III outlawed them because of the wounds they were causing.
You needed to stand up and be able to use both arms to fire the English Longbow. Which was, until the French started winning the 100 years war, the be all and end all of ranged weaponry. However, the French soon figured out that a wounded, and even maimed man could sit 50 yards away from active combat and shoot the musket just fine. He might even be able to reload it. Whether or not he hit anything remained open to debate, but the function was still there. The early firearm was also obnoxiously loud. Which, given the "god fearing" nature of most commoners pressed into militia at the time, was nerve rattling.
The Crossbow's obvious downsides were the amount of time / strength required to reload it and it's relatively short range. The faster you wanted to shoot it meant the less pull on the string, which meant less force from the bolt, which meant less impact when it struck a target. Given that the crossbow was also a point and shoot weapon opposed to arc high and fire across the battlefield, gravity was not a crossbowman's friend, either. There was no trajectory arc for the crossbow. Given a modern choice? Invest in a .22 rifle and a box of .22LR shells. Then, take a 2 liter bottle. Seal that bitch on the end of the barrel with some duct tape. Congratulations. You have a makeshift suppressor that might work for 1 or 2 shots. Either way. At least you're not drawing attention to yourself trying to reload a crossbow.
On Water & Fire Supplies: Actually I made a point to mention that I keep a Zippo, lighter fluid, and a box of wooden matches in addition to my unopened pack of Bics. Water is still easy enough to come by, depending on the disaster. But the obvious solution is to check the faucets you come across. Sooner or later, someone has a well. Sooner or later someone paid their water bill before everything went to Hell, and since there was nobody around to actually press the button to have it shut off from the Utility Company's end...
On Most Recent Scenario: I'm vetoing whoever gave me those stupid orders. Seriously. That bus isn't coming anywhere near me. I'm not wasting what extremely valuable, almost non-existent medical supplies I have at my disposal on a bus load of
people targets. There are other, better, more equipped places for them to go. And if there isn't? Then guess what? The healthy and able bodied need to be kept separate from the others and not draw attachments that will ultimately, get them killed. If there are no medical supplies to be had, and nowhere else nearby to divert that bus of people too? They're on their own.
That said. If there is somewhere else I can take them, or even more likely, somewhere else I can raid to get those medical supplies IN TIME, then I'll try. I'm not cruel for no reason. I am practical, yes. Tactical. Efficient. Perhaps even callous. But I am not needlessly cruel to sick and wounded people.
In that type of situation, assuming I can't take what I can carry and be on my own way, what I'd do then, is turn the floor over to those most medically able. I'd stay the hell out of their way. And I would let the experts do what they're best at. Which means, I'm on the "Away" team. It'll be my job to go load up at the nearest gas station for coffee, salt, sugar, rolls of paper towels, cleaning supplies, and whatever first aid kit they've got available. I'd also do the same for whatever garage / mechanic is nearby. Gasoline and Oil are fuel sources. Any place that has chemicals is also required by federal law to have an accessible first aid kit. So, the gas stations and garages are quick ways to find alcohol, things that can be used for bandages, tools, fuel, and if you're lucky, food that hasn't spoiled. These places are also a lot less obvious than say, a Walmart. It's also quick and easy. You're not going to waste time digging through overturned isles to find the one bottle of peroxide left.