Can the Firewire be used to get still images from SD Card in GS400. If not what is proper way.?

No. You can use USB2 or a separate CF card reader.

I greatly prefer a card reader; no software is required and it doesn't tie up the camera.

<<<-- Originally posted by Chris Hurd : I greatly prefer a card reader; no software is required and it doesn't tie up the camera. -->>>

But there is a wear and tear by frequently plug/unplug the SD card using card reader.

Regards
Leigh

Nah. They're made for this sort of thing. You're not going to abuse an SD card from putting it in a card reader one too many times.