The flicker, as mentioned, can apparently be seen by some and not others so not necessarily a problem with the tv. I have never noticed any flicker issue with any of my plasma tvs and neither has my better half.
Motion: again, I have no issues with any type of motion and I have IFC switched off (never considered any improvement when playing around with it at the different settings). I watch only Sky+HD and Blu-ray, so could it be an issue with your Freeview HD broadcasts? Is the Freeview HD through the tv itself or through an external box? Personally, because I have a sat dish and a connection to the TV I only ever watch FreeSat HD but only for short periods because I switch to Sky after power on. If using Freeview HD on the tv itself, have you checked the quality of your aerial / connection? I had mine replaced last year including all cabling (to include connection to my sat dish) so I know I have the best possible reception - something I considered worth the investment as it is a one-time cost that should last my lifetime.