My herp first aid kit includes painkiller-free Neosporin, Betadine, Chlorhexidine (basically the same uses as betadine, but a bit milder so better for use around the mouth; usually at CVS under the brand name Hibiclens), Honey (for frogs only), the hardest, crappiest Q-tips around (they stick to saliva and teeth less if you have to do anything to a snake's mouth), and unflavored pedialyte (can be used on any frog or reptile; diluted in water for a soak to get them to drink a bit and replenish nutrients. Works best on frogs though since they just absorb it through the skin). I also keep Hydrogen Peroxide around, but have only ever used that diluted down in cases of wild rescues that have gotten so bad that they had maggots and necrotic tissue around wounds. It's pretty harsh stuff, so should only be used to 'nuke' something that is really serious; frankly if it's to the point you need that, a vet would probably be a better option.

The way you're thawing and stuff sounds fine to me. You just don't want feeders at room temp long enough to allow bacterial growth.

In my experience husbandry has to be pretty bad for actual scale rot to happen. At some point during your snake's life, you'll probably see a scale or two get discolored, and you can either ignore it or swab with betadine, but that's generally no big deal. But in the cases of scale rot I've seen that were medically significant, the husbandry is usually just wildly off base. So as long as you do what you're supposed to you probably don't have to worry about that.