Panny G5 100-300 Stabiliser questions

I switch IS on on my 100-300  when I need it and because I do a lot of moving subjects, by default it is turned off on the lens and in the camera menu.  What happens when the lens switch is off and I use the menu stabiliser option 2 panning.  Does anybody recommend that I should be using this for BIFs.

What happens if I have the lens IS on and select the menu option 2 does this cause some other effect.

Does menu item1 have exactly the same affect as switching on at the lens.  If they are both on presumably it doesn’t matter and the effect is exactly the same as if only one was on.

--
My Galleries are at
http://picasaweb.google.com/trevorfcarpenter