I think they would have mentioned if the jacket looked chewed on.
I'm not sure animals walk around with $1000 in cash often... Most of the ones I have met don't at least.

But I'll keep an eye out for it.

A report I saw yesterday mentioned that the jacket appeared to have both human and animal hair on it. If that's accurate, I'd consider the presence of animal hair as a clue. Of course, that may not have been accurate. The news media is notoriously inaccurate when it comes to aviation. It's also possible the jacket including identification cards and cash washed off of the mountain.

As for positively identifying the plane, every airplane is required to have a metal identification plate with identifying information (make, model, serial number, etc.) That plate is mounted on the rear fuselage near the tail. I'm reasonably confident that the ground search party had the identifying information and was able to confirm the plane's identity as being the one Fosset was flying.

As to the crash itself, if the plane flew straight into the side of a mountain, it seems unlikely the engine would be 300 feet away (uphill). Some of the pictures seem to show the plane hit on an incline, perhaps a glancing blow. It's hard to tell from the sketchy information released to date.

One thing I learned from years of flying in Colorado is that if it's windy, you can encounter very strong downdrafts when flying towards mountains. Those downdrafts can be strong enough to overcome your plane's ability to climb. The preferred technique is to approach a mountain ridge at an angle so that it'll be easier to turn away from the mountain if it doesn't look like you're going to clear it. That might be one possibility of what happened to Fosset. A Bellanca Decathlon has a good climb rate but at that altitude, he still might've found himself unable to clear the mountain. It's also possible the visibility was low and he didn't see the mountain in time. A cloud covered mountain is known as "cumulo granite." Very unhealthy.