I think one of the things that can be difficult to get to grips with is the directory structure. Like "where is every thing?" and "where should I put this?".
The distribution you use will have variations and its own way of doing things.
If you really want to get to grips with Linux, install it on your desktop. Ubuntu should make it relatively painless, but you'll end up in the command line whatever version you use.
google Linux Comands as well. This could help you with your search. But forums are also a good place to find information too. I wish you the best in luck on this.
There are lots of flavors of Linux. I would agree learning some basic commands by reading and then installing on your desktop to try it out would be your best bet. Linux isn't for everyone as it can take thinking and isn't exactly the same as the Windows based PCs most people rely on.
There isn't really much to know, the best thing is to learn as you go perhaps, if you need help with something and someone shows/gives you a command, check it out and see what it means.
hmm, if you got the money yes... but if you rely your staff too much, once they leave you for some reasons you will be tied up... so a basic knowledge is still required. .