The Fanuc 6 is a great control. I hope you can find an operator's manual (they're out there) so you can come to appreciate some if its features. First, set the Manual Absolute switch in the position where it works and leave it alone. I can cause all kinds of grief and was only put there to assist in setting up fixture position. Second, it sounds like you may have confused work coordinate offsets (G54,etc.) with tool length offsets. They are on different screens.
As for DNC, this control will NOT drip feed through the serial port. It will only load programs into memory from the port. It can, however, drip through the tape reader port if you have one of the many "Behind the Reader" interfaces that are available.
Warren
www.uptimecorp.com