SGM,
We had a late Sept hunt and no flies what-so-ever. That could sure be different year-to-year and if early Sept, could be some flies. If you're on a lake for your hunt, you'll likely get some bow spray from the boat, along with some wet weather anyway, wherever you are. Doubt you can get any gun oil through TSA, but one of the guys had some individually packaged gun wipes that came in handy, and several of us made use of one wipe for several guns.
Fishing pole? I took one and fished, but didn't hook any pike. Others did, and it passed some enjoyable time. Take some magazines or books. If you tag out early, or the weather is bad, you'll keep your sanity. Other than that, good quality clothes/boots/gloves/hats to keep you comfortable. If you like to have a drink, pack some power/weight-type booze as weight is $$. A case of beer in camp was $80...if it was available. Take a camera for sure. If you're pushing your luggage weight limit, wear some extra clothes on the Montreal-to-Kujuaaq leg. They weighed our bags (including your rifle/case) at the Montreal hotel. Take some earplugs. You may use them for OTHER people snoring, but I found them useful so that I couldn't hear the others yelling at me for MY snoring!!
One thing our crew did was spend two nights in Montreal on the way up to make sure our luggage/rifles made it, and allowed us to see some of Montreal, which was fun. Just something to consider.
Good luck!