Just from what I have read, the total area in sq feet that you have added to the home, has increased, I may be that your or original electrical was under sized or had out grown todays needs, just a guess, the sub panel that is there is most likely wired wrong, my bet is it does not have a isolated neutral, or you do not have eniough spaces in the old panel, this could be the reason, the electrician needs to open the wall, also I did not see anything about inter connected smokes, and remember another circuit for the bathroom GFCI.
