Oh boy. This kind of scenario is what's called on this board TEOTWAWKI (The End Of The World As We Know It) and it's supposedly off topic. However, yes, dry grains in sealed containers will keep pretty well, there are places that sell what you want, and water needs to be rotated every 6 months or preserved with chlorine, and/or purified at the time of use. Yes, if the earth's rotation stops, your running water will probably also stop. There will probably be some pretty amazing climate changes too. And one side of the earth will be in perpetual daylight whlie the other side will be perpetually dark. If you think you may end up on the dark side, you'll want lighting equipment too.