IIRC LyX lets you save the docs in pdf format.
vim, is a text editor (the most powerful editor I've seen). You probably have it already installed as it's the default editor in unix/linux.
If you plan to use an editor for long time, I encourage you to learn vim or emacs (both are extensible and can be used through ssh).
Vim is a modal text editor, so at first it's quite strange, but IMO it's worth the time learning it.