Hi Debbie!
5 is a great time to bring your son! They are old enough to understand that a Disney vacation is a really BIG deal, but at the same time not too old for the entire experience to feel magical in a way that only a child can experience. If he's like my daughter (now 6), he'll be talking about this for a very long time :-)
The Pirates League is a fun experience that will inaugurate your son as an official pirate sailing the seas! In fact, the entire family is encouraged to do this (recommend reservations). You will be asked the packages you're interested in. You can either purchase a costume beforehand or they have some in stock (not part of package). You then have your name forever changed to a swashbuckling pirate. They will sit your son down and apply his pirate face (3 eyes, skull face, etc.). They will then say a pledge announcing him as a pirate, then he goes into a secret room to have his picture taken. A terrific experience he's sure to remember!
Family pictures using Photo Pass is a great idea! Disney photographers are strategically placed throughout the Parks. You should get your Photo Pass before your trip, which the photographers will use to scan. You can then get the pictures developed at the Park at a Photo Center, or you can order them later after your trip via online.
As for resorts, the 2 that my children thoroughly enjoyed were Animal Kingdom and Coronado Springs. Both have a number of amenities that are very kid-centric!
Have a Disney Blast of a Time on your trip! Hope Captain Jack Sparrow Jr. have tons of fun!