Backing up I thought I'd mention the door handle fitting. Using the dimensions provided, I extended the hole in the existing door:
Then tape on the template (the square on the template should measure exactly 100mm so you can check scaling - I found printing actual size it came out perfectly:
I was a bit tight on the cut and being an early version the rivets had cap heads rather than countersunk so there's a few bits where I had to file a bit more. Also on my doors the fibreglass at the wide end was very thick so in order to get the spreader plate in I had to grind out a recess for it :
Fits in nicely, I had a cut off bolt at the broad end but have now been supplied a slightly longer bolt with an allen key head so that it can all be removed with the door skin in situ:
I looped a bit of string through the loop on the cable. Fastened the widget to the door release arm (sorry no photo) then attached the door skin to the existing door. The string allowed me to pull the cable through to where it was needed then I removed the string and by touch hooked the cable over the widget on the door. That's it:
Notes:
The handle is a two stage activation press the button (near the front works best) and the handle pops out - it will not return until you fully open the door - pull the handle to release the door. If the cable is a bit loose on releasing the handle won't return to fully closed.
Do it with the windows up
Don't finally fix the skin into place until you have the position of the widget in the right place, it's much easier to adjut with the skin off.
If the cable is too tight then the door will work first time but it won't go back fully and then you can't open it again - including with the interior handle.
If the cable is too loose then the door won't open on the new handle but will open on the interior handle.
You can check by manually closing the latch with your finger or a scredriver shaft without actually closing the door, give it a good few goes as mine worked for the first 10 times then stopped as the cable bedded in and then needed adjusing.
Other than that it was reasonably straight forward.
@argy has provided extra templates for drilling an extra hole in the old door to give access to the the second bolt holding the handle in, but I haven't drilled this yet.