Yes, correct on all three counts Martin. Mike was John(nies) younger brother.
However, his stints in Reaction and Smile were transcient. In football terms - he was in the squad, and very occasionally got a game as substitute, but he was never really in the team (if that makes sense). Partially because he never really was that great a bass player, but, was still a very handy person to have around.
I believe Mike still lives in the area, and is now the managing director of a haulage company. When Queen first began their concert career, it was Mike's company who initially transported their equipment.
"Listen to them. Children of the night. What music they make."