Good morning! And a big howdy from a fellow Texan who lived in East Texas!
I am in your boat as well, being this is the first time I will have cruised. I can try to answer as much as possible, and hope it helps. Al little background here. I will be traveling with my 10 year old son, and another family that has three kids. So i understand the quiet you talk about.
1. Ports. I am all about the cruise myself, could really care less about getting off the ship. I am actually being brave and going during Spring break. Only going because my son was on the honor roll for an entire year, and this is his reward. All the islands are the basic structure, white beach, nice sun, beautiful water, and very over crowded.
2. you are right on the length of cruise, short cruises are for the weekend warriors who are stressed and need a quick getaway, and anything longer then 7 would be tedious. the 5 day or 7 day, in my opinion, seems to be perfect, without getting bored. I'll let you know.
3. Since this was my first cruise, I chose not to go the expensive route, and got an outside cabin, with no ports. I was thinking of an ocean view, but decided that i won't be in my room but for sleeping and changing, so spend less. If I like it, then next time I will budget for a better room.
4. As for the rest, I leave out of Galveston, so i drive there. it isn't all that far, and I have friends in Houston so i stay with them. Hotels on the Island are horrid, but off peak, they come down. All the other ports, Miami, California, etc., they have most of the same itineraries as The ships leaving Galveston. Only time i would really fly anywhere is if I were to take as Alaskan cruise, which is over my budget, way over!
5. You are going through hurricane season, but since you really aren't in it for Ports, then if they cancel the port, you will still be on ship. Hurricanes don't hit every day, so go for it.
6. Is the cruise good for you? I have no idea. The ships are huge. You can get up and move if it is to rowdy. If you want quiet, try a line that carries more of an adult mixture, and during school times. I can't say what the stats are on this, because cruising is very popular now. I have heard that the more elite you sail, the less likely to have a party boat.
I hope to be able to post a good review when i get back, and to help with questions. Since i will be traveling with my son, 10, he will be "parked" in Camp Carnival the entire time, so I can wonder the ship and get some good research from watching.
I hope i have helped.