2) include spare foot wear and a bag to put dirty/wet clothesand
5) bringing snacks to share is a nicer gesture then only bringing enough for yourself. it sucks watching your passenger eat. school yard sharing yadda yadda.
(drivers can often run out of time or forget to pack a snack)
6) always offer to compensate for gas money. they may not always accept cash but it should be offered or an option to buy them food. Most will happily take a coffee on the way out and one on the way back