Most cruise lines require a dive within 12 months. What this really means is that you need to have been on a dive within 12 months for the first dive. After you dive the first port you can then claim your last dive was yesterday.
I've been diving all the places you list. All of them on one cruise is pretty amazing. I might skip St. Maarten if you don't want to dive every port but all the other ports are great ports to dive.
There is one dive operator in St. Lucia (I think they are Scuba St. Lucia) which does a shore dive from Anse Chastanet Resort. There is an amazing marine park right off the shore with some great wall dives. The problem with the location however is that just down the coast is a fishing village and there are fishing boats racing over head occasionally. Because of this, Scuba St. Lucia wants to be sure you aren't going to panic and go to the surface. So they have to do a mask and regulator recovery at the start of the dive (in the bay). If you cannot do this without effort you might want to skip going with them. If you can do this, they have a great dive. They aren't making you do this test to be a pain. A few years back a diver had a mask flood, panicked, went to the surface and got hit by a boat.
Grenada has some nice wrecks to dive. Last time I was there the government did not allow operators to build docks. I had to wade out to a small boat then the small boat took us out to a larger boat. So you have to be in reasonable shape to dive here.
Dominica has some wall diving and a dive call The Champagne Reef. Dominica is a volcanic island. There are small bubbles coming out of a reef. You can lay in the reef and it is like being in a hot tub. Really cool.
St. Kitts is just a nice dive. Good marine life. I think they insist you have a dive computer. If you don't they'll rent you one.
In Tortola you will almost definitely dive the Rhone out by Salt Island. It is an okay dive. It is quite rusted out so you can safely swim through it. There are a lot of other sites in the area but last time I was there on a cruise we went to the Rhone.
Curacao is definitely a good shore diving island. I have gone diving with The Dive Bus. I also heard good things about Ocean Encounters. You can book your dive by going to
The Dive Bus website. You'll need to get a cab to the shop. Before you get in the cab agree on the price. Once you set the price you can get in the cab and know they won't change their price. When you need to get back to the Cruise ship you can have Suzy or Mark call a cab for you. Remember to agree on the price before you let them drive you back to the cruise ship.
In Bonaire the choices are endless. I'm sure there are dozens of good recommendations you'll get from people on here.
I'd recommend googling the island for the recommended dive shops and seeing of they have a cruise ship package. Some of the dive operations will have a special for cruise ships. They pick you up at the same dock as the cruise ship, take you to boat to the dive shop, suit you up, take you diving, bring you back to the cruise ship. Makes it safe for you so you don't miss your cruise ship departure. The only place I've had a close call was Curacao. They had internet trouble and I didn't bring cash. Then it took a while for the cab to show up and haggle the price. I still made my ship before it left port. I suspect the cabbie quit haggling because he didn't want me to miss my ship.