Linux certification links
You have a lot of questions and there is no easy answer. The only cert that I know of that is distribution specific is the RHCE for Red Hat. For distro neutral certification I think that the LPI is more industry recognized.
If there are companies you want to work for that only use Red Hat only then get an RHCE. If not then the LPI would be a better choice.
As far as paper books, I like LPI Linux Certification in a Nutshell by Oreilly. Still cant' compare to the LPI tutorials on IBM developerWorks. Look on the link I posted above.