Hi Philip,
Welcome to the site.
(1) Your external frame should be fine for now assuming it fits, is large enough, and is comfortable. If you decide to upgrade your gear the pack is usually the last thing to change.
(2) Check with local rangers for conditions specific to your hiking area. There is safety in numbers. There is a recent thread about lightweight hand-guns. In general terms most hikers don't carry. Your milage may vary.
(3) The local grocery store should get you most of your food. The food forum on this site has a ton of recipes and ideas.
(4) This site has a lot of info on general hiking. Gear lists, equipment choices etc. What works for you is what is best for you.
Good luck with your trip. <img src="/forums/images/graemlins/smile.gif" alt="" />
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Deeds can't dream what dreams can do. e.e. cummings