Maybe I can help with the Aruba part.
I worked for a Dive Operator there recently.
There are only a few operators in Aruba and the two largest ones (Red Sail Sports & Pelican Adventures) accomodate cruise ships. Aruba is not generally known as a "diving destination". So even when the big ships come, the boats are usually not too crowded. However, you will be there in peak season.
I worked at Pelican Adventures. Before moving to Aruba, I had visited the Island 15 times. I tried all of the major operators. I always prefered Pelican because of the staff. I always felt the most comfortable with them. The people are friendly. Pelican is a smaller company than Red Sail as they operate only on Auba. The owner is on site and customer comfort is high on his priority list.
Both Red Sail and Pelican offer a 1:00pm and 3:00pm one tank dive most days. If I knew what day of the week you were to be there I could give you the schedule.
Most likely the "Pedernalis Wreck" at 1pm and the "Antilla" at 3pm . This is a reverse profile set up! The 1st sit being just 25 ft and the second 55ft. You may want to consider this.
There are night dives on tuesday and Thursday. Night dives are usually the "Antilla". Don't worry about doing the same dive twice, It is very different at night. The ship is 400 ft long and takes many dives to explore the whole thing. I have done this dive over 100 times and still enjoy every one.
The story (keep in mind this is part history & part local legend. I cannot guarantee iots accuracy)
The Antilla is the most famous of Aruba's wrecks. This german freighter was in Aruba's waters during WW2. It was suspected of supplying German u-Boats. Once Germany invaded Holland, the were considered the enemy by Aruba (Dutch). The ship was near Aruba and was surrounded by Dutch Marines. The captain, anchored off Aruba's North West shore, asked for time for his crew to gather belongings and surrender on shore. During this time, the crew super-heated the boilers. Just prior to leaving the ship, the captain opened valves allowing sea water to enter the ship. When the cool water reached the hot boilers, there was an explosion that virtually ripped the ship in half. The Antilla sank, lying on its port side. The main mast still penetrates the surface, as does a section of the starboard side.
The crew were taken prisoner and sent to Bonaire (a prison camp at the time) where they spent the days drinking rum and hitting on Bonarian women. (this is why so many people from Bonaire have blue eyes

)
After the war, these prisoners liked Bonaire so much, they did not want to return to Germany. So a group of them opened the first Carribean resort in the Area. The buildings--The prison of course. The prison was converted to a resort. That resort is now the "Divi-Flamingo Resort"
The ship itself has become an artificial reef. There are multitudes of reef fish. The blown apart mid-section reveals the boiler sections. The wreck is easily penetraed at this point. The large cargo holds allow lots of room and there is pleanty of sunlight. Max depth 55 ft, this is a dive for both beginners and seasoned divers. The ship is on its side. The bottom is almost like a wall dive. Look up and see the colorful sponges and corals encasing the hull with the bright sun shinning overhead. Also sometimes stingrays hang out in the sand 50-100ft away from the wreck. There are several VERY LARGE green moray living there, so be sure to look under things (especially in the blown up section).
Water temp is around 80-82f. Visibility ranges from 50-100ft, just pray for a good week. The vis is much better on the south coast, but no one offers pm dives there.
I suspect that even if you make your own arrangements for pick-up, you will be picked up by the van who is there for all the cruise ship divers. You may be on a different boat tho. Sometimes the operators send a separate dive boat out just for the cruise ship divers, in which case,. perhaps just doing the ships agenda would be better.
You may want to try to find out if there is a private chartered boat for your crise ship prior to making arrangements.
Another option would be a smaller operator who may be able to take you wherever you want to go. In that case i suggest "Windie's Water Sports"
Hope this helps,
Andrew