I forgot to comment on other issues. About the new social class system, I can leave it to you (you seem to be well informed about that). About loan words, I agree with you to an important extent. May be we should use an expression like: "..and to a lesser degree/extent on grammar, rhetoric etc."  to make clear that the influence on these aspects was less important. Another important thing is that here we are talking about Persian spoken during that period not today's Persian, that is why I tried to include only studies focusing on that era. About the other stream of influence, I will go the university library to check linguistics journals. I remember seeing an article discussing Arabic-Persian inter-influence from a linguistic but also a historical view.   .