I would not charge a lipo pack at a rate higher than 1C unless specifically recommended by the manufacturer. Can it be done? Sure. Should it be done? I don't feel that it's a good idea, but maybe my understanding of the cell chemistry is out-of-date.

For storage, shooting for a voltage around 3.7V corresponds to a charge level of ~50%, which is a good compromise (you want to lower the voltage in order to decrease the self-aging of the cells, but not so far that there is an unreasonable risk of self-discharge to dangerously low levels).