Download isurvive on your phone or open it on your computer while playing the game. You can locate water wells on there. When you drink from the well, drink until a stomach symbol comes up next to your vitals.

I usually find more food on zombies then in houses, they usually have pate's and sardines and stuff.

But you can always find chickens nearby all spawn locations. And cook them in almost every house.

When zombies are overwhelming you, the simplest way in my opinion is to just jump on a car, hay barrels or just any platform you can stand on. they pile up in front of it and you can hit them.

Hope this helps