It doesn't matter one iota what the wing loading is.
If you are trimmed for level flight in an airmass and that airmass rises you WILL rise with it unless you do something about it!
Not quite so. An aircraft in level flight flying into a thermal of rising air will tend to rise, and if in the rising air for long enough will eventually rise at the rate of climb of the thermal. However, it takes time for the aeroplane to accelerate vertically and the heavier the wing loading the less quickly will it rise. Usually it will have flown right through the thermal and out the other side before it attains anything like the ROC of the thermal.
That's why a glider (low wing loading) will feel thermals as vertical 'shocks' much more than a jet transport would.
When flying though isolated patches of rising air (thermals) the heavier the wing loading, and the faster one flies though the thermal (extra speed reducing the time exposed to the rising air) the less the aircraft will rise.