Hoppes #9 is a very mild solvent, and I have never experienced it affecting the blueing of a firearm, something I cannot say of bug repellent! If you wipe down the firearm with solvent, wipe it dry before applying oil as the oil will be reduced by the solvent. You might want to purchase an air dryer for the inside of your safe if you are concerned about humidity induced rust. There are electronic and chemical air dryers available from most of the larger gun dealers. Surface rust when visible can be carefully removed with ###-fine steel wool used alternately with gun oil.
When maintaining your firearm, you want to be able to disassemble the piece as far as the manufacturer recommends, and clean all accessible surfaces. Because I don't know what type of firearms were are talking about, it is difficult to give you further advise, but when speaking in generalities the following normally applies.
Copper fouling as well as carbon fouling needs to be removed from center-fire rifle barrels, and the bolt faces cleaned also. Shotguns may have issues with plastic fouling from shot collars. Copper in rifle barrels is often addressed with an ammonia based solvent, however these products must be given a bit of time to work, but if left for more than 15 or 20 minutes rust might be created as the ammonia evaporates and dries. Anytime a rifle barrel is treated with such a solvent it should be patched dry then followed by a patch wet with a good grade of gun oil, followed by 2 dry patches, and you should be good to go. The shotgun barrel does not require a strong ammonia solvent and a product such as Hoppes #9 works just fine with a good quality bronze brush.
Stay away from the cheap gun cleaning kits. One piece coated rods are considered better then jointed rods, although the jointed steel M-16 cleaning rod is a valuable field cleaning tool. Get the best quality bronze brushes of appropriate size you can find - good ones are supplied by "Plenty of Patches." Which reminds me - use only cotton patches. The synthetic patches won't work nearly as well.. A spray can of WD-40 will be useful for displacing water from wet weather or created from bringing the gun into a warm room after being outside on a cold day. Wipeout is a foaming bore cleaner which I've had good success with for removing copper fouling if left overnight, although it might take the color off aluminum coated parts.
Hope this helps
