#1. "RE: My Menu & FV Lock?" In response to Reply # 0
No, but assigning it to a button can be listed in My Menu. FV lock only works from a button. It locks the flash value in when you've focused in on the area of the frame that you want to lock it for. I can't really see how that would work from a menu item. Every time you touch the shutter button or back button AF to activate the meter, the menu closes.
FV lock is also very good for photographing people or animals. Sometimes the metering pre-flash triggers the blink reflex, so when the main flash fires, the eyes are closed. If you FV lock first, the next time the flash fires will be for the actual image.