I really like your idea to reach out to seniors through the mail to disseminate education about falls prevention more rapidly.
Building onto your idea, another way to reach out to seniors (by mail) could be through elementary schools, children could be the ones sending the postcard or kit in the mail to their grand parents or great grand parents (i.e., just like every year they reach out to their families to raise money for the American Heart Association). The 'chain' could also be setup in a "pay it forward style", so they could read the information and then send it to another person that is 65+ and so on.
I like the idea of including coupons too!, it has to be something seniors would be really interested in getting , maybe they would have to call a # to acknowledge receipt of the kit to get the coupon (so those could be better tracked). The idea of reaching out in a massive scale to 65+ with something like chain letters, pyramids, pay it forward it's very interesting and truly proactive.
It could also be useful if product labels and produce in the grocery store are linked to "alternative recipes".These could be in the form of a code that you scan on your phone at the point of buying that product. For example, if I am buying oranges a code link to how to make marmalade and scented candle with orange peal. These alternatives could change all the time and promote less waste