I was going to say that prison ship could only be hulk and matriarch would be Ma. And credulous fellow would have to be fool or gull.
Yes, you are right. I am sure GANDALF is the password, and having read a post I made upthread I remember the connection between the clues (and also the password) was that all were connected with a Ring / in some way a ringbearer if you counted the Ring of Barahir (it was inspired by Galadriel's previous one, which had Ringbearer as the password and in which the answer to every clue was a Ringbearer). I also had to put some of the answers backwards to get a password, and I think Galadriel did that with one of hers, too.
The last of the clues should be easy now.