1)when the creature burrows its rough tongue into the guys brief and tight shorts ,were would it enter the tight shorts?
At the waistband, in front.
2) once it had got into the tight shorts ,what would it find different about,that part of its meal?
It would be easier to chew and have a more musky taste.
3) would it use its tongue to cup and grasp the contents of the shorts?
It probably would because it would naturally use its tongue to move food around in its mouth.
4) how would it eat whats in the shorts ?
Given the size of its jaws and the speed with which it ate the turtle-like creature, it would be one very quick bite.
5)would the shorts still be whole when the creature spits them out ,would theybr damp/wet with saliva /digestive juices.
They might be a bit torn, but would be whole. Yes, they'd be wet.
6)what would Willis E. Davidge find when he went looking for the guy ,what would he think had happened to him .
Just the shorts. At first he would think he went skinny-dipping, but when he couldn't find any trace of him, he would start thinking terrible and mysterious things happen on that planet.