Hiya and welcome to the forums!
First off, you should've posted this in MsgPlusGeneralTalk. And yes your first suggstion is a good one. And your second suggestion, there is a feature in plus that your contact could use to show you. If he/she has Messenger Plus!, then all he/she has to do it type (!VER) and hit enter, and it comes up the Msn Messenger Version, Windows Version, and Plus Version.