When filling in the Absolute Title can this be a new chosen title?  or does it have to relate to govcorps identification? I.e John of house Jones. When govcorp identifies one as John SMITH?

Yes…   new Title.. ” No one gives a better title than oneself. ”   You and only you decide your Title.. slaves however have a name chosen  for them.    

Also when my Fiancé registers can she also come under my new house name? 

Again  you are correct…