I would also concur about the sleeping bag--the Campmor bag is probably the cheapest alternative for down. It's more like a 30-35* bag than the advertised 20*, but you can always wear more clothing inside when it's colder.

Most of us who are older need far more padding than a Z-Rest provides. I have to use an insulated air pad, 2.5" thick, or I'm in misery. Try it out on the floor at home before you decide it's a keeper! (Yes, a lot of camp sites are that hard!)

Re the pack, whichever one you ended up getting--put all your gear inside, including the weight/bulk equivalent of a week's food, and hike around the house (or the neighborhood if it's a clear day and you keep it off the ground) for several hours. If it isn't comfortable, send it back! Pack fit is almost as individual as shoe fit!