Linux is really just a variant of Unix. Most of what you learn is completely translatable between the different *nix platforms. There are some differences in terms of implementation but these are normally small. If you are applying for jobs that are as a *nix administrator, chances are that 99% of the software you will use will be exactly the same no matter what *nix platform you are on, unless it's bespoke in which case the company you apply for will provide training.
Fedora is a Linux based distribution. If you have used linux before you may want to look at something like FreeBSD for a different take on the *nix implementation.
If you are going to buy a book, buy a book that complements the particular flavour of *nix that you install. There are plenty out there and I'm afraid that I don't really know any to recommend, learnt most of what I know via friends, colleagues, uni and the net.
Can anyone else recomend any?