Just another gun-nut's personal preferences (everything I know, I learned from these forums):
I only use grease on my semi-auto rifles; on my pistols I use G96 exclusively (I find that grease gets way too dirty and keeps particles inside the gun). Don't worry about the finish wearing off, that'll happen no matter what. Just use the wear patterns as a guide for the parts you need to lubricate. Guns that I intend to keep in the safe for a while I leave pretty wet, those I intend to shoot soon only get a light coating of thin oil.
On the rust issue, it all depends on where you live. If you're near the ocean, I'd seriously consider keeping a dehumidifier near your gun safe, or at the very least throwing some moisture-absorbing packs in your safe.
Also, I would definitely recommend you buy a silicone- or wax-soaked gun cloth (G96, Hoppe's or others). I use one to wipe down my guns before putting them away; leaves a nice, thick sheen on your guns that protects metal surfaces against corrosion for a long while.