Yes a good trip leader would help (to the best of their abilities) to solve all of those problems. They will often use the resort manager or cruise director to also help since often the goals are the same. Happy customers = return customers. I will always book with the groups that I book with because I know they will fight for what their customers want or need (within reason).
Now, if you decide not to book your air/or any other travel through the trip leaders business then they will prioritize their customers who did book through them. I see this often with travel in Indo since flights are constantly cancelled or late. It might be great to get that hot deal on a flight and not pay the booking fee but when things go wrong and your flight gets cancelled then its pretty much on you to deal with the consequences. I will happily pay the extra to know that they are watching the flights and constantly giving us the updates that we need to know. I have still seen trip leaders try to help these same people who refused to book their air etc. with them and often solve their problems with smiles on their faces.
Now, if you decide not to book your air/or any other travel through the trip leaders business then they will prioritize their customers who did book through them. I see this often with travel in Indo since flights are constantly cancelled or late. It might be great to get that hot deal on a flight and not pay the booking fee but when things go wrong and your flight gets cancelled then its pretty much on you to deal with the consequences. I will happily pay the extra to know that they are watching the flights and constantly giving us the updates that we need to know. I have still seen trip leaders try to help these same people who refused to book their air etc. with them and often solve their problems with smiles on their faces.