Need advice on microphone with 3.5 connector for DSLR

Not sure if this is the correct forum.  However, I am getting the Panasonic GH-3 in hopes of reducing if not eliminating the need for a dedicated video camera.  I have to have an external microphone and I will do minor editing.

I will use the microphone to pick ambient sound or even someone inside 6 feet that may be talking like in a parade that I may shoot.  I know that lavalieres are not practical and a shotgun mic may be too narrow of a choice.

I was looking at B&H and see some of their accessory suggestions, but wanted to ask here or where ever that should be directed.

Last, I was thinking about the Camcaddie as a portable travel type rig.  Any suggestions because if I need to use a zoom a video camera has a toggle and its one hand operation.  A DSLR with a zoom you need two hands.

What techniques do you use to keep the shot steady and portable?

Thanks