Can i view and edit values of G54,G55 etc?

You can view them by looking at the associated parameters. I think that the parameters listed there are read-only, but it is a fairly quick experiment to find out.
Or you can see them in some GUI screens if you turn on the full DRO
You can set the parameters in a variety of ways with the G10 commands from MDI.
The offsets are stored in thelinuxcnc.var file (or whatever your .var file is called in your config) and an be edited there with a text editor, but you would need to make the edits with LinuxCNC not running, or your edits would be over-written on exit.