Have a great trip! And Happy Anniversary!!
Your wife may be disappointed with the soups. My wife who has been the Soup Queen lately due to a dental issue, now resolved, doesn't recall either having French Onion Soup or seeing it on a menu last month. Now if you want to ask about Lobster Bisque...
The island is dry, not having had significant rain in 3-4 months. That helps to keep the mosquito population down. However, it also depends on how well where you're staying has done mosquito control, and how well their neighbors have done mosquito control. I saw very few last month. I also used mosquito repellent regularly anyway.
Cocktail bar... that's a tough one. We are more likely to have cocktails at the villa than out, and perhaps post-lunch/dinner rather than pre-lunch/dinner. Keep in mind that the OUI limit in France is half of the typical US OUI limit, .04 rather than .08, so a designated driver is a good thing to have. Still, with .04, you can have a good time without being stupid.
So, places. Wanna hang with the locals in a world-class down and dirty sailor's bar? Le Select in Gustavia. Want to bring it up a few notches? Bar Oubli across the street. (Bring cash for Le Select and Oubli). Maybe a bit of a sunset view? La Cantina in Gustavia. Upscale, Victoria's at the back of the harbor.
Island drink. There are two ways to go here. Traditional island and tourist island. The traditional island drink is a 'Ti Punch, pronounced Tee Poonch, which is basically a shooter - Cane syrup, 100-proof Rhum Agricole (some say it tastes like gasoline), and a squeeze of lime. Exercise caution. Sip it, shoot it, doesn't matter, you're downing a shot of 100-proof rum. The traditional tourist drink is a Planter's Punch, a concoction of rum and fruit juices. I tend to make 'Ti Punch at the villa after I'm in for the night, and have a Planteur before lunch or dinner. Wanna keep costs down? Pre-game with cocktails at the villa, but keep that .04 limit in mind for your DD.