[kop316]

> Does MMS make it easy to have a group conversation, or does everyone have to remember to do the equiv or "reply-all" (add everyone's number in) when sending a message to the group?

It depends on the client, but yes, MMS makes it pretty easy to go.

> Do you get free SMS/MMS included in your plan? (My American Aunt has always insisted SMS was obscenely expensive and refused to use it to communicate.)

Most common plans that I know of have unlimited SMS/MMS/Phone calls (unless you get a really cheap one).

> Do you get Data as standard with the plan? (Eg is it that people can't easily use WhatsApp because they don't have data when out and about or is it that people just won't agree which IP product to use in the first place?)

Data is generally standard with a plan. SOme only give you a limited allotment, and some give you some version of "unlimited" (i.e. if you use too much they will start to throttle you).