I would look into building a larger capacity auto feeder out of PVC pipe that can be filled from outside the coop/run, and a drinking pan elevated on blocks up against the fence that can be filled with a hose. That way if you have a kid doing it, they don't need to go inside. Some chickens are sneaky, and wary of strangers, so should they escape at the door, the chicken watcher may have a very difficult time catching them. Especially if they're not familiar with chickens.
When we go out of town, if it's only a couple of days I put out 3 drinkers and the giant feeder. All drinkers are elevated to keep them clean. If it's a week or more, we have sister-in-law stay or look in on them, and to get eggs and clean up. We did find other local chicken keepers to share responsibilities with through a local Yahoo chicken group. Sister-in-law doesn't know chickens, and isn't very good at catching them, so I try to make everything as easy as possible by having access to the important things without opening any doors.
But really, we just don't go out of town. Our dogs are crazy for anyone but us, so if they can't go, we don't go. There's only one person they'll listen to and who can handle them, and that's my dad. He's not a chicken guy. Previously we've had to split the animals up based on who could do competent care for what. Still cheaper than hiring an expert to come stay.
If you want to know how much food and water needs to be out, set it all up as if you're leaving. Then watch, and do nothing, as if you're not there. You can tweak the system before you leave and get a lot more peace of mind.
Great ideas, I really like the test run. I need to start another thread as this one got me to thinking, can birds be alone Sunday pm to Friday PM if you have the right setup? I can't have chickens until we move to the country but that could be years away. Right now we are only there on weekends.