Congrats of going to Bonaire, I think you will enjoy it. My first trip outside US was a couple years ago (to Aruba) and I was a littel nervous about what to expecct. Since then I have traveled outside US several times (including Bonaire) without incident. Here are a few tips that were given to me by Scuba Board members for my first trip, which I still use to this day:
If you plan to use your visa / mc or any other card you should contact your card company let them know your dates of travel and where you will be going...this will prevent your card from being declined for suspected fraud.
I register my trip with the State Department (web page) and obtain location and contact information for the US embassy or consulate in my destination region.
I make 3 copies of my travel itinerary, passport, resort info, consulate inforamtion, credit cards I will be taking along (including 800 customer service number), health insurance & drug cards, dive insurance cards, as well as phone numbers for banks, family/friends, primary doctor. I keep 1 set with me, seperate from the originals and in my room safe... the other 2 sets go to 2 seperate family or friends. I have never needed this information and hope I never will BUT in the event of an emergency I feel more comfortable with it readily available.
Give yourself plenty of time to get through airlines check-in, baggage & customs, Weigh your bags and do not go over your airlines weight limit...THEY WILL CHARGE for overweight / oversize bags.
Finally and most importantly, relax and enjoy your vacation. As for the other things you had questions about; Most places will only bring your check when you ask for it, the prices are listed in both US & Guilders, and TIP IS USUALLY INCLUDED (look for something indicating service fee). If you are with a large group most they might ask if people want a seperate check, this makes the end of the night calculations super easy. Had no troubles using V/MC, especially since I contacted card companies about my travel prior to departure. All the rental vehicles I had were standard (stick). Be sure to keep the customs form you will get on the plane in a safe spot...you will need it when you leave. You will also pay your departure tax at the airport on the day you leave...there is a round or octagonal building right in the center of where airlines are checking people in...it will be marked. Do not forget to pay your departuretax or you will have to get back in line all over again. Odds are your cell phones will not work while you are there so you may want to consider renting a phone but be careful sometimes cell phone rental and call charges end up costing more than a call from your resort room. Check out a restaurant called "Casa Blanca". It is close to the Dive Flamingo resort, looks like a little hole in the wall but the food is GREAT !
Enjoy your trip.