If completing this for my son who is now in the US Marine Corps - do i note this somewhere and will i continue to file the same way going forward for him?

You cannot legally sign your son's tax return.  I suggest you print it and send it to him.  He can then mail it out.  EMail is not secure and i do not recommend it.

The other alternative is to have him prepare and sign a Power Of Attorney FORM 2848 designating you.  Once you get it back you will have to mail it along with a FORM 8453 which authorizes you to mail something that should have been attached to a tax return.

If you can get the POA FORM 2848 you may be able to bring it to a local IRS office.  You can find one here using you zip code.  To find a Local Office:     Local IRS Offices

As a member of the military, he can obtain 100% free access to tax consultants and financial counselors with military expertise. Contact Military OneSource anytime, 24/7 at  800-342-9647 to take advantage of this benefit.