Get one of those black plastic handle grips from Weber that fit on the tab of the lid vent. Once installed, that will provide a nice, big, easy grip to turn even the most "gunked up" lid vents. Also, don't clean the inside. You want it seasoned good with smoke, soot, and carbon. It also helps keep it sealed better around the edge. Keep the cook grate clean though.
The mold you are hearing about is only going to occur on the cook grates where bbq sauce was left behind. It's the sugar in the bbq sauce that causes it. Each time you build a hot fire inside, it's killing all the germs and bacteria. If you want the outside looking clean and sharp, get some of that Weber exterior grill cleaner. It comes in a spray bottle and works like car wax cleaner. It will give your kettle finish a great shine.