Problems using tramp

[Gary .]

Basically, I seem to have two problems.

1. Although I can connect successfully if I specify everything in the
"Find file or URL" minibuffer (i.e.
address@hidden:/my/path/to/file), if I set things in my config
file as so:
(add-to-list 'tramp-default-user-alist
             '("ssh" "host.example.com" "user")
)
and try to use completion, it doesn't work (the connection appears to
work okay, but the password is refused).

2. The "Find file or URL" minibuffer keeps returning, even after a
sucessful file opening, and it's kind of distracting as the content is
normally quite long (at least two lines). Is there any way to stop
this?