Second time the explanation about the booster runes didn't go away for a long time. There should be a way to actively dismiss it and halt the game play until you do.
There doesn't seem to be a way to rotate either the active skills/units or the boosters which can make the boosters rather pointless if none of the skills is pointed in a direction you could connect them...
I had the miner of course, and a soldier in the second play. Is there also some sort of healer unit?