As for whether the insurer has the right to subrogate against the friend for damages, this would not be permissible because this would be essentially like subrogating against one's self.  (See, specifically, A.2. under the "OUR RIGHT TO RECOVER PAYMENT" section of the PAP.)

Regarding whether the friend's auto policy would cover PD to the owner's car if the owner decides not to submit the claim to his insurer, it would depend on the language of the friend's policy.  But, if the friend's policy contains the typical "OTHER SOURCES OF RECOVERY" clause found in the PAP, then the friend's coverage would be excess over the insured's because the insured's policy is another collectible source of recovery.

Finally, as far as whether the loss would be considered a chargeable accident if the owner submits the claim to his insurer, it depends on the particular insurer.

The policy is rated on known drivers and their history; because the presence of a totally unknown driver that isn't in the household and usually can't be rated disrupts the filed rates, some companies chose to charge for the accident regardless of the driver because it's the only way to rate for the insured's allowing others to drive his car. Other companies will only charge if it's a driver on the policy, while others may add the driver to the policy and charge for the accident (although that's pretty much restricted to non-standard companies). Some companies consider anything that's collision at fault, regardless of who's driving.  Still there are some companies that will let it go unless there's a known history of letting other people drive the car.