Using "Power of Attorney and Declaration of Representative" forms for deployed family member

My son is a U.S. Marine deployed overseas.  I need to be able to prep, sign and file his taxes for him as well as any additional documents.  I'm aware of IRS form 2848 (Power of Attorney and Declaration of Representative) that will allow my son to assign me and my wife as his representatives.  Maryland has form 548 which is basically the same thing. Both forms have instructions that refer to having a Power of Attourney.  My son has one that he is sending to us now.

 

What I need to know is...

1. What do I do with the forms once my son has signed them?

2. What do I need to do with my son's Power of Attourney?

3. Is there anything else that I need to do or should be concerned about?

 

Thank you.