Wash before first use. Do not microwave.
How do I clean them?: Just wash inside and out with warm water and soap. Then rinse and hang dry or towel dry. Wash after use, as food sitting in the bags and left in your lunchbox can stain.
What kinds of foods stain?: Yellow mustard, carrots (if you use the same bag day after day)... and others
How long should they last?: This is very individual. Just like finally getting rid of an old plastic container. The length of time that you will be able to use them depends on your usage. If you use them everyday with care and wash them nightly they should last dozens of times.