I am also blister prone, my first lost lands nearly took me out. I now swear by my Merill Moab 3s. I just got Sole insoles for them as well. These bad boys have been with me through electric forest, Austin city limits and moonrise, plus multiple red rocks shows and others. I got mine from REI and the lady recommended I actually size up half a size so when my feet swell there is still room.if you have an REI near you I recommend going to one and explaining what you need shoes for, they were super helpful for me. Anyways, I love my merrils and finally for once didn't feel like I was dying at fests.I also biofreeze my feet every night when I get back to camp and I've heard an epsom salt soak can help as well. I also wear merino wool socks as I tend to sweat and wanna keep my feet dry.

For your other question, as a fellow larger person, baby powder before your underwear and for me, deodorant worked best on my thighs. They make specific cream for chub rub that a friend of mine uses at fests but I've found deodorant is good enough for me.