Computers are good at that! Glad you enjoyed the scene.
1) Would the Crocodile return to the shore and try and eat the arm that came off?
Probably not because he was in such a frenzy of shaking at the time that eh wouldn't even remember ot. Most likely, scavenger birds would pick the meat off the arm.
2) The guy in the picture looks to pack a fair sized package in the front of his shorts,when the croc eats that part would it be able to tell that it’s the guys reproductive area?
No. Reptiles don't emit the same pheromones or scents that mammmals do, nor do their sex organs resemble thos eof mammmals, so he wouldn't recognize what the parts were.
3) Would the crocodile swallow the once tight denim shorts whole with what`s left of the guy?
4) Once it lays down on a sunny sand bank to digest it`s food ,what parts of the guy will be digested first , how long to digest the guy .
Fats (like the private parts) organs would be digested first. Then muscles, finally bones. The process would be underway within a couple of hours, but the bones would a day or two.
5) What will happen to the guys denim shorts inside the crocodiles stomach ?
The stomach acids will bleach them out and make them more ragged, but they will be identifiable in the croc's droppings.