UNIX for Dummies Questions & Answers

I'm learning UNIX on my Mac (BSD) and quite like it. I'm a newbie, but I think I'd like to eventually find some work with UNIX/LINUX. But I'm not sure where to begin -- there are so many versions and job options, it's kind of overwhelming.

A friend suggested learning Debian to start out with and getting an LPIC certification. Another suggested Red Hat, saying that Debian isn't used a lot in business, and Red Hat certifications increase your chances of getting work. He also mentioned learning CentOS, saying it's Red Hat in another form, and it's free. Yet another suggested a Red Hat Certified Technician certification to start and going from there.

I guess, for the experienced users out there, my questions are these for now:

1. Can anyone tell me what kind of IT jobs/positions there are and how they differ from each other, and how I might choose which one I'd want?

2. Which versions of UNIX/Linux are out there, which ones are good to know and which of the two are better to know? Does anyone use UNIX these days, or is Linux the way to go?

3. Which certifications are available, which one(s) should I start with and what do they do?

4. Where can I get training on these OS's? Are they online, at some school, or what?

Thanks for all your help

Well,
Why would a company want unix staff?

You answer that, you have a clue on what to look for...
In Unix world you are expected to be to change plateform or flavour...so the most important is having a (very) good general knowledge of "UNIX administration" and in a company it means not "How can I change my screen definition" "Idont like my window colour" or installing games etc... but dealing with servers having from time to time heavy loads network issues, disk failure etc... with plenty of concurent users...
So being a master of vi is a good start...

vi refers to what, unless you mean the UNIX text editor program?

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vi refers to what, unless you mean the UNIX text editor program?

Yep the editor
I cannot imagine a sysadmin not knowing vi...

Ive seen many issues because people used fancy GUI editors... on configuration/system files...

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But then, I looking at your request from a sysadm point of vue...
Perhaps were you interested in development, here the flavour has less importance, since all unix should have most commands called the same, its just a question of using the man and looking at the arguments which may differ (e.g. ps ax vs ps -ef...)