I use two things exclusively to clean my lenses (whether it be the front or rear lens element).

1. Rocket blower (or similar) to remove the larger particles;
2. A LensPen - I normally use the soft brush to remove any stray dust then use the cleaning tip. It's the best tool I've found by far - the tip stays moist for a very long time and they're cheap to replace. Streak free, no risk of damaging the lens element (if you remove dust etc first) and it's small enough to get into all the corners of your lens (into the rear lens element for example). I won't use anything else.

For cleaning contact points any soft cloth should be fine.

To combat lens fog the best tools are ziplock plastic bags and patience. Put your camera and lenses in a ziplock bag while still inside then give them at least 10 mins to get down to temperature before you take them out. It's fine to leave them in the bags until you need them. You basically need to wait long enough for the air inside the sealed bag to get to ambient temperature before opening it up otherwise you're essentially creating steam with the hotter air from indoors. I used this while travelling Europe in the winter and it works well. It also helps to have a well insulated bag. My backpack is very well insulated so you just leave everything in the bag for half an hour or so to cool down until you take your gear out and you should be ok.

Hope this helps.

Ben