I hope I can provide a little help.
Most airlines have many partners of affiliates, and if they have to make changes or a flight is cancelled they will change you over to another airline for that leg of the flight, in a manner that is suitable to you. This is generally done at no cost to you (or at least it has never happened to me). Also if you miss your connecting flight because of their goof up, they will rebook that, put you up at a hotel if required and/or give you food vouchers if it is going to be a long layover.
Here are some senarios that I have encountered in the past (and remember I live up in the great white north on the Alaska Highway so air flights can be tricky to begin with).
1. My flight to Orlando this spring is booked on Air Canada with FF points (booked over a year in advance). Air Canada partners with United on this and my leg from Orlando back home was to go via Chicago leaving at noon( i originally wanted to go via toronto but no FF seats were available). Three weeks ago I checked the status of my tickets and United had cancelled my flight from orlando and I was booked to leave at 8:30 am.
After I jumped up and down a few times I phoned the airline and calmly told them that unfortunately I would still be on the cruise ship and it would be impossible to make that flight. They quickly apologized and changed the flight to the 2:00 pm flight via Toronto- the one I wanted in the first place (they had to give me a 'revenue' seat, in other words one that usually requires payment, at no charge).
2. Once got stuck in Indianapolis when my flight to toronto was cancelled. Air Canada paid for a ticket with Delta (not even a partner airline) to fly out the next morning and I received vouchers for a very nice hotel, supper, breakfast and shuttles to and from the airport. Be warned, this can take a while to get, and you may get a run around.
I do not believe you can get insurance for this kind of thing. The main thing to remember is not to panic, have the 1-800 numbers for your airline customer service, and do not be afraid to ask for the local manager. I have even called the 1-800 # in front of the manager and after I explained the situation, the person on the phone asked to speak to the manager. After about five minutes where the manager got redder and redder, he hung up and things magically started to happen.
You have paid good money for these tickets, and you are entitled to your relaxing trip.
Hopes this helps,
DL