welcome sanchester! you've come to the right place!
you should check off that he wants his application processed in Kingston
I just want to respond to your question about making your application stronger for your husband. I will just tell you what I submitted, I don't know if it's right or wrong but I find examples are easier to follow for me. I sent in all phone bills, we top up digicel online and I have a phone card I top up online so I sent those records as well, our msn logged conversations, facebook profiles and emails back and forth, all emails back and forth, every picture I had of us together or with each other's friends and family, our wedding photos, our wedding itinerary and invoice, letters from both our family and friends to validate our relationship - especially our parents, copy of my passport pages with the stamps of travel to/from JA, all my plane tickets, itineraries, hotel vouchers etc., ... I can't think of anything else I sent right now.
you have to send in his original birth certificate but a copy of his passport (I made sure to copy the birth certificate first) I also sent my original marriage certificate - from what I read in the instructions I think Mississauga needs 1 copy and Kingston needs the original.
I hope that helps!