1) Opening once a week is fine - make sure you don't dawdle and let the temp drop too much taking photos and such...
Edit: Open every 2-3 days when approaching hatch date as Oxygen requirements will increase.
2) 82% is too low
3) Yes you can wipe water off the eggs with a paper towel-make sure the paper towel is fresh
4) Do not check them daily (if you have to open your incubator to do so)-you will cause temp. variations which could reduce viability/create defects
5a) The eggs are tougher than most people think
5b) Be prepared to remove eggs that die during the incubation process - don't panic - it happens - just make sure they are in fact dead before discarding.
5c) If you are suspending the eggs on light diffuser grating you can saturate the Perlite with water if you want - ratios aren't that important if the water doesn't touch the eggs -I use Perlite so the water doesn't splash when I pick up the containers-whatever works for you.