I'm afraid I don't know enough to really understand your posting.

I can address a couple of your statements though ( I think ):

Does a glider perform differently in an updraft? Seems like it, at least in the degree of back stick needed to maintain a circle. This is no surprise, I'm sure. The "updraft" contributes to the force needed to reduce the downward acceleration of the glider, so less lift force is needed for the job, so less increase in AoA is needed. I'm probably missing your points here and just describing what you already know. I'm sorry about that.

What about a "level" turn in a glider? As far as my very limited experiences have shown me, a "level" turn - a turn during which the glider does not loose altitude - is what I hope for in a thermal. Actually, I hope to gain altitude in a thermal but that doesn't happen for me very often. Does the glider's airspeed decrease in such a "level" thermal? Not if the "updraft" is adequate.

I'm sorry I don't follow your statements about approaching stall speed gradually or slowly. Over my head I'm afraid.