Possible move with children

Your kids will probably love PR. If you live near the beach, they will never get tired or it. If you live in the San Juan area, there is an excellent surf school for kids on Playa Aviones behind the restaurant/activity base known as Mambo Jambo in Piñones. I can try to dig up their contact info for you or when you are there just go to Mambo Jambo and they will square you away. They are very pleasant, professional and safe.

There is also a place in Isla Verde called Casa Cuba that has a large range of activities for kids like recreational sports leagues and other good stuff. (Reasonably priced as well.) http://www.casacubapr.com/. You are not expected to be part of the Cuban expat community to join. Most members are not Cuban.

There a many more examples of kids activities. It can be hard to find anything on the internet in PR but these activities are out there.

If you enroll your kids in private school, they will make plenty of friends very quickly. If you home-school, it will take a little longer and may be a little harder but they will make friends through their activities or, if you live in a condo, with the kids of other residents. (Their circle of friends will probably be much smaller if they are not in school.)

When you go to activities, just start talking to people and you will make friends quickly with other parents. If you invite some kids to your kids' birthday parties, you will receive reciprocal invitations. PR is probably one of the easiest places to make friends in the world.

Definitely do not send them to public school.

The Kids will have no problems in Puerto Rico: there are many good bilingual schools such as Robinson,St. John's, Baldwin, American Military Academy, TASO, Notre Dame,(just to name a few) where they will meet children from Puerto Rico and all over the world.  Teaching is primarily in English but with the Puerto Rican experience. They will also love the fact that they can swim 12 months a year.  Check out http://www.puertoricodaytrips.com  and http://www.onthewayapp.com/  for tons of things to do in PR.
As far as you and your husband are concerned, ask your husbands company if they will provide a one day or two day Cross cultural training or orientation; I work with several relocation companies who provide this service to incoming or outgoing exces and their families to ease them into life in Puerto Rico.  I facilitate a lot of the training for major pharmas and for the most part, the assignees appreciate the info.
Come, it will be a great adventure. 
By the way, if you are bi lingual most spanish spoken in Puerto Rico is NOT standard Spanish:  for example if you ask for a glass of Jugo de naranja.... you will generally be greeted with blank stares and immediately labeled as a gringo.  Here we call it JUGO CHINA (no di either).... it is believed they took the name from the labels on the orange bags which were imported from China way back when! Even the juice cartons call it CHINA!!  also no Puerto Rican pronounces the S in any word...you'll adjust. ;-)