Sconny, what model is your stove? Mine is similar in that the sooner I turn the air down, the hotter the stove gets because the secondaries have a greater affect. Not sure if that applies to the Shelbourne since different models work differently. In my case, the secondary air is controlled along with the primary air and that may make a difference.
Yes, this is true of mine. Once the stove itself is warmed up and has a good bed of red coals, I like to get a new load of splits roaring and fully involved (the "flames of hell"), then start reducing the primary air. This will get the stovetop temp up and the flue temp stabilized or coming down. Continue reducing primary air every 15 minutes or so, until there are no more flames on the logs and all of the flame is hovering at the top, around the secondary tubes. At least that's how mine seems to work best...