Can my 2013 Prius II currently equipped with driver door only smart key access be : a. Programmed to unlock / lock all doors upon touching driver door handle? b. Can a OEM "Smart Key" front passenger door handle be installed & programed to function as if factory install?
a: Yes, it's in your manual. Watch this video, it's at the 1:34 mark. b: You can install one, but it needs to be wired properly. See this thread.
I would recommend not programming all doors to unlock upon touching driver door handle for safety reason. It's not really desirable if you're in a dangerous area. Instead, you should have the dealer program the fob to open all doors at once and can use the fob whenever you're carrying passengers.