Ugh, I just wrote this HUGE response and it didn't go through. Grrr...
Anyway, welcome fellow St. Lucia bride! We're so excited to have you.
I have been to St. Lucia before. FI and I stayed at Coconut Bay in Oct. 2007 and had a great time. You actually may want to look into this resort. It is all-inclusive, kid friendly, and located in the southern end of the island near the airport. This is a much quieter end of the island, so getting some privacy for a beach wedding would be no problem at all. Anyway, just thought I'd throw another idea out there.
For my wedding, we are also gettig married on Pigeon island at the private beach. Afterwards we are going to Jacques for cocktail hour and dinner. After that, we're headed to Villa Capri (where we're staying) for dessert, dancing, and drinks. (Ha ha, I didn't even plan those all starting with "D".) We've hired a band called Ten90 and the reception will be held on the villa's deck. I'm so happy we chose to go the private villa route. The property manager, Kris, is arranging everythign and she is fabulous!
For our honeymoon, we are staying at Orchid Cottage (about 5 minutes away) for 3 nights and then we're off to Punta Cana. I know that sounds a little strange, but we wanted to visit another island while we were down there, and I'll have already been on St. Lucia for a week and a half at that time.
For your honeymoon, another place you can look into is Rendevous. I hear it is similar to Sandals (couples only, AI) but without the commercialism. I think people either love or hate Sandals.
For restaurants, I do not believe it is cheap to eat out on St. Lucia. The last time we were there we only ate at the resort or on tours, but this time we're not staying AI so I've been researching some places. It can definitely get pricey.
You will love St. Lucia, I guarantee it. Congratulations and feel free to ask us whatever you want. We'll do our best to answer!