Jim,
Re: Shooting in the rain - I have a photo vest made by The Vested Interest, called the Magnum, that has a loop on the back designed to carry a monopod. The loop of cloth, about 8 inches long sits vertically between your shoulder blades. While I have never used it to carry a monopod, I have modified it slightly by closing the bottom end so that it will hold an opened umbrella overhead. I am sure that it looks very dorky, but it does work if the wind isn't bad and you don't try to move around too fast.
If you look close, This picture shows the monopod loop with black monopod.
Re: Polarizer + lens hood - I am not aware of any solution for using both, but I haven't found that it matters a great deal. Since a polarizer is most effective when the sun is at a 90 degree angle, the effect of lens hood is diminished. If you really need both, I don't know of any solution other than removing the hood to adjust the polarizer, but I would certainly be interested if someone has found or invented a workaround.