Absolutely recommend the Fantasmic dessert package to them. We are WDW vets and Peter Pan fans and we LOVE the Peter Pan section of Fantasmic. You get to watch Peter and Hook swordfighting on a pirate ship-doesn't get much better than that! DL Fantasmit is so much better than the WDW version. We don't even go to Fantasmic at WDW anymore. We think the dessert package is well worth it to get a seat.
Although it is not a guarantee, we have seen Captain Hook every time we have been to Minnie's breakfast, so it is a pretty good bet. We think that character meal is better than any of them at WDW anyway, so even if they don't see Hook, they will see a bunch of fun characters.
Peter Pan often shows up for meet and greats and play around the castle sometime during the day, but it is hit and miss. They might be able to ask guest services and get exact times.
One thing to warn them is that the Peter Pan ride at DL, does NOT have fast pass. The lines get long just like they do at WDW, so it is a real pain, especially or us as since it is one of DD's (6) favorite rides and she doesn't care for the mountains, we are used to having a new fast pass in our pocket for Peter Pan every time the time is up for us to get a new fast pass. At DL, we usually only ride it once in our entire trip. At WDW on a MK day, we might ride it 4-5 times with fast passes.