FPNI
My 2 cents: If you are just concerned about storing food for a small family unit, go the 1 gallon route. If you are set up in a group, go for the big 5 gallon bags.
I've used a 1X4 board with an iron to seal the bags and it works great-both big and small bags
I tend to use medium sized absorbers and place one in the bottom then another 1-2 on top for a 5 gallon bag. I seal the absorbers in a mason jar between buckets to keep them closer to their full capacity and/or give me the ability to take a break from time to time.
Don't forget variety. Pinto beans and white rice are great but you can get Great Northern, Black Beans, Red Beans, Variety bean packs, several different grains etc...etc...etc
Don't forget spices. Most are salt based and way overpriced. You can do a lot with salt and pepper, cayenne and a few herb seeds (for long term gardening)
If you're not by a source of salt, go overboard on it. We have no sources of salt in MN. I have planned abundantly for this need. It's cheap and your body won't work without it....