I'm also a DL parental non-rev.

All the bookings are through your son's Delta login which only he is allowed to use. He cannot give you his Login information. Delta does not provide the ability for 'Pass Riders' to access their system so he will have to be your 'Travel Agent' for and Delta non-rev or discount ticketing. He can send you links to web pages which provide more detailed information.

If you are going to use discounted tickets, no problem. Once they are booked they are like any other ticket that you have purchased and you can manage them directly through the regular Delta web site or over the phone.

If you non-rev domestically, depending on the route and when you're travelling, you may find it very difficult or impossible to get on flights due to your relatively low priority code and the high passenger loads.

If you non-rev internationally, again it depends on the route and when you're travelling and you need to have alternate plans. I always have sufficient 'Miles' in my account to purchase a last minute award ticket. I've only had to do that once in the last 7 years but due to US weather conditions and the backlog in travel, it would have taken me over a week of waiting to non-rev back to the US. You should also be prepared to sit in back, not D1, and even buy a ticket on a low cost carrier if that's what it takes to get home. Also be prepared to fly to other destinations that may have better opportunities. For example - DL has more daily flights AMS-DTW than AMS-JFK. Once you get back across 'the pond' you have a lot more flexibility. Remember, you can only non-rev on DL metal, no partners. You also want to either have an international calling plan on your cell phone or a Skype account to be able to contact your son when you need his help.

As GagaPilot implied, parental non-revving isn't for the faint hearted.

Good luck.