"
Some 737 will have internal front stairs but it is rare to see them fitted or if fitted working."
Really ?......
Having worked on the 2 / 3 / 400 series as an engineer, I would less than politely suggest you are unfamiliar with the reason for airstairs...notably to facilitate access at locations that do not have airbridges.
Removal of the airstairs induces CofG changes hence even if locked out, they are invariably fitted.
And a GPU is essential if the operator's policy is to shut down the APU asap after arriving on stand as well as for night stopping engineering and cleaning operations.
"
best not to touch the door handles at all because they must remain in a flush position or may cause damage if left out in flight".
Opening and closing the doors is perfectly safe once the escape slide has been disarmed and even if the girt bar does become detached from its holder, it still takes a considerable force to activate the slide. The door handles are easy to operate and even if left not fully flush will lnot cause damage to the aircraft.
My late grandmother enjoyed her eggs fried, scrambled and poached by the way.