I have a North Star unit, same basic unit as your QF7100 (most p/n's are the same, your firebox is bigger and you have some additional options), remove the front fasicia (4 screws, designed to be removed so you can clean the bottom area around the fans out) and put the magnetic thermo on the steel chimney pipe above the stove. After you re-install the front fascia, you can view it pretty easily through the top vent plate. It's not in your way or an eyesore this way.
Anyhow, the temps on these magentic thermo's vary quite a bit, I have the rutland version, and I usually run a cycle after a new load, I leave the air full open until the temp reaches 500->600 (anywhere from 10-20 minutes, needle straight up or 10degrees or so beyond past straight up), then I open up the 'timed air' then set the air to almost full close, I close it down to about a just a shade, mabey 1/4" away from full close. If you have dry wood, it'll secondary burn for several hours this way. Late in the coal stage, I open the air up to 3/4 or so open and it'll maintain a decent heat output for another hour or 2.
I've had it up to 750 before, didn't seem to cause an issue, but that's getting to the edge of my comfort zone.
As far as the thermocouple kicking the fan in and out. 2 things. First, on every load, scrap away all the ash in the center of the floor, get the ash off to the sides or out completely, get nice clean red hot coals in that area. The thermocouple that controls the fan is right underneath the floor here, so keeping the insulating ash away from that area helps that alot. I find I need to remove ash at least once a day to keep the most optimized burn cycles going. Usally I remove some ash first thing in the moring when it's had a chance to burn down alot and there aren't so many hot coals. I wish there was a rake tool or something, but I move the shovel around and get the coals off to one side and get most of the ash out.
2nd, I wired the thermocouple override switch in my setup (was outlined in the instructions). It's a simple light switch next to the variable fan control. . Most of the time, I just leave the override switch on, because the thermocouple kicks the fans off too early in my opinion. Only time I won't have the override switch on is when I leave for a few days and the fire's still burning when I leave. Thermocouple controlled fan is a neat idea, but execution is another story. Alot have reported these going bad fairly often too. Anyway, if you keep the ash from insulating, the center area of the stove, even with my override switch off, the fans never kick in and out, they just shut off too early.