Stand alone HAL and User Interface?

I am trying to build a user interface for a simple single axis machine, a saw stop/pusher for a double cut mitre saw. I've started and have most of the general framework of what I'd like it to be set up in Glade, but I'm struggling with the python side of it.

The machine will have 2 basic modes, Stop mode and Pusher (besides homing).
In Stop mode, the operator will input the length (for outside cut lengths), the axis moves to that point, and he cuts or for inside cuts the operator inputs a length and a width and the axis moves to the length+2(width).

In Pusher mode, it is a little more complicated, with several input fields,
overall length
width (used same as above)
cut lenght1
# of pieces of length1
cut lenght2
# of pieces of length2
cut lenght3
# of pieces of length3
kurf width (would be on a seperate settings page)

So for example, cutting a 12ft piece of moulding might use these settings:
144 = overall length
0 = width (using out side measurment)
12 = cut lenght1
4 = # of pieces of length1
16 = cut lenght2
4 = # of pieces of length2
24 = cut lenght3
1 = # of pieces of length3
0.25 = kerf width

After punching in all those numbers I would like a place that will show the amount of scrap left over, in this case it would be 5.5 inches.
Operator would then press the start button, axis would move to 143.75 (overall-kerf) and waits.
Operator makes cut, sensors in the saw indicate when the cut cycle is finished, then the axis moves lengh#1+kerf, and waits (1st cut1 complete)
cut2, (same as cut 1 except using length2)
cut1,
cu2,
cut1,
cu2,
cut1,
cu2,
cut3, and then moves back to 143.75, repeat

I would like to be able to save the settings of overall length, width, cut lenght1, # of pieces of length1,... as a file, so the operator can recall settings of each job they work on.

I'm also at a bit of a loss thinking up exactly how to home the axis without the normal linuxcnc underpinnings. (there are limit switches at both ends of travel)