1) How do I not let the edges rust? On my last board the tip and tail would rust, I'd file it off, and then it would come back.
Wipe your board when coming home.
2) Am I using Ptex right? I have "clear" ptex but it comes off as a brownish burnt thing. I'm using a lighter, waiting until the ptex catches fire, then dripping it in the holes, but it is coming off as a brownish things with black flakes.
There is a proper technique to prevent black flakes from getting in the p-tex. Look it up on youtube
3) Under my bindings, I have little bumps on my base, and I'm wondering how to reverse that/make it not happen again. Is it the screws? Do I need shorter ones? When I loosened them, my bindings were wiggly although I only have 3 screws as I lost one somewhere.
Get shorter screws. What kind of bindings are you using?
4) Am I waxing right? I have household iron that I use exclusively for waxing, and it has holes in it. I drip the wax on, and then iron it out going back and forth. The wax will smoke. Am I doing it wrong?
Turn the temp down. wax should not smoke. This year I got a real waxing iron. Makes a huge difference.