Water
How much should I store per person?
I believe the recommendation is 1-gallon per person per day. This would allow for cooking, cleaning and personal hygiene. So a family of 4 would require almost 1,500 gallons of water for a 1-year reserve. Logistically, this is difficult to manage. Depending on your location and the threat that you envision, some method of collecting and purifying water (ground water, well, spring, rainwater) might need to be considered.
How should it be treated for storage and should it be treated or filtered before consumption?
Sealed containers of water bought at retail require no treatment and, according to the CDC, have an indefinite shelf life if unopened and stored in a cool, dark location. However, the translucent containers prevalent in larger containers might start to break down after a few years.
Tap water from a public utility subject to chlorination and other purification measures theoretically, again per the CDC, require no additional treatment. But does need to be rotated every 6 months.
Well water and spring water should have 3 to 5 drops of chlorine bleach added per gallon, and be rotated every 6 months.
If maintained as per the above, no additional treatment should be required before use.
In containers I am considering powerade bottles, 2-3 liter soda bottles, 5 gallon water jugs and 55 gallon water barrels, any thoughts on this?
It's a battle between efficiency of space and convenience in rotation. Powerade bottles are probably too small to be effective, 55 gallon barrels might be too large to rotate. I prefer 2.5 gallon jugs of spring water and rotate them into general use, so none are usually more than 6 months old.
Food
I've never tried the long term foods but the manufacturers claim they have a 20 year shelf life.
Would they be edible beyond that time?
Probably. If you read the books by Cody Lundin you'll learn he's pushed far past what most people would consider reasonable in experimenting with "expired" food, including food that has turned rancid, been infested with insects, etc. It depends on what you consider to be "edible." I expect that taste and nutritional value would be reduced. But 20 years is a long time. If you amortize a $5k investment in long term foods over 20 years that's less than a family outing at McDonalds every month.
How do they taste and are they filling? When I looked at Weiss I think it was, a daily ration was one serving of one half a cup of food.
Some of it tastes good, some of it tastes lousy. Stock-up on spices and hot-sauce for palate variety. Whether they are filling or not is somewhat an academic question. They are more filling than doing without. As long as you're getting the necessary minimum amount of calories, vitamins and minerals, your body will eventually adjust to a reduced volume diet.
What about grains? What should I store, how should it be stored, and for how long?
Whole rice, wheat flour, corn meal and oatmeal. Not grains, but I'd also lump dry beans, salt, sugar and yeast in my bulk preps. Sealed in opaque, oxygen-depleted containers (oxygen absorbers or nitrogen saturation) I believe these will last at least 5 years, salt and sugar forever.
What are your opinions on survival type gardens? Are they worth the unwanted attention they might attract?
I like the idea of a vegetable garden from a self-sustainability perspective, not just survival. You'll appreciate the fiber after eating all those dehydrated meals, and will need some sources for vitamin C. Also raising chickens and goats for eggs, milk, cheese and meat. Do you have a pond or cattle tank on your land? If so, maybe you can farm fish.