I don't know exactly how many times you can reuse lard, but I have read that, each time you heat it (assuming you get the temperature relatively hot), you are breaking down the chemical bonds and making it less stable. I've rendered lard once before, and used each batch twice when frying. I just didn't feel comfortable using it a third time -- was worried that the bonds had been destroyed and it had oxidized or something, particularly since my frying was just done in a pot and wasn't temperature controlled.
As for storage, a glass jar with a tightly-fitted lid in the fridge will do the trick.
Everything in moderation, including moderation.