I agree with you fully on your central points.  

I would simply like to point out, in case you have never heard the following, that St. Thomas was not 'against the Immaculate Conception.'  

Rather, this common depiction, that has been long promoted, ignores his specific texts that do not contradict what that dogma implies at all, as was shown long ago by Nobert del Prado, in his Divus Thomas et bulla dogmatica "Ineffabilis Deus".

Sincere regards.