Customs was not that bad, just make sure you have all the paperwork that the pearl shops give you plus any receipts. Also, I locked my pearls in my luggage which was checked in (for some strange reason I felt safer this way??) and the customs guys said that it would have been better to carry them on- why exactly I don't know- for security reasons maybe.
I wound up getting a pair of single pearl drop earrings in white gold from Nicos Pearls on our first trip into Vaitape (main city of Bora Bora) and then a pearl strand bracelet for my mother (and one for me too!) at Robert Wan.
In terms of what to pack- I definitely overpacked! I lived in my bathing suit and bathing suit coverup ( back then the Juicy couture terry cloth strapless tunics were in style), and flip flops! At night I would wear a cute sundress or a flowy short skirt with a tank top. Oh and I brought my own snorkel gear (mouthpiece) b/c I easily get skeeved.
You have to sign up for a sting ray/shark feeding tour. I think a tour run by a compnay called "Sharkboy" is the most famous one, but honestly the island is so small I think the excursion companies are all interconnected.
Oh- and bring an underwater camera. Hy DH and I brought a few disposable underwater cameras b/c we were unaware of a a waterproof "case" that can be purchased to cover your own digital cameras- allowing you to dive to a certain level underwater with your digital. I think the quality of pics will be better with this case (in comparison to a disposable) just check your camera company's website.
Sorry to babble- I got excited
!!! PM me if you want me to forward some pics.!
And don't worry about the language barrier, EVERYONE speaks English. Tourism is their #1 economy. The trip there will fly by....literally....especially once you start heading over the islands, you'll be too enthralled in the beauty to notice how long everything took!
I have been to Hawaii, Costa Rica, St. Martin, Bahamas, Martinique, St. Thomas, and Dominica, and IMHO they do not compare to Bora Bora. It was amazing and I am very jealous of anyone that is going! We had an all inclusive package at Le Meridien (a couple of nicer hotels have popped up right next door) and I would agree that you should venture into dining out on the island a couple of nights... People raved about Bloody Mary's- but the food was so so, if you want to go just for the atmosphere- do it. There is a name of a small restaurant that requires reservations well ahead....I will try to think of it and post it...it was some french name- my DH and I unfortunately did not go, but heard raves from others.
....check out Robert Wan, and Nicos, and Perles de Tahiti on the main island of Bora Bora...but be super nice to your DH before you venture out to these shops 
