Sportsmans warehouse in Soldotna is probably your best bet for purchasing a long gun if you so choose. If you're planning it for bear protection you likely won't need it as many of the lodges around there are already equipped for that and so are their guides. If you're headed to the Russian definitely bring a weapon and/or bear spray. If you want a nice dinner eat at Mykels they have the best crab legs anywhere and all their food is phenomenal.
Shipping fish home make sure you get it vacuum sealed and frozen, Eds Kasilof Fish Processing near the bridge does a nice job. Once its frozen solid and you pack it in insulated styrofoam/cardboard 50 pound boxes along with gel packs which you can also get from the fish processing places. It will stay frozen and good for nearly 48 hours for travel if you're flying out of anchorage you can rent cold storage at the airport, not sure if they're doing it with Covid. 10th and M does a great job in anchorage with fish processing and will store for you as well. Have a great trip