Yes, that guide should get you what you need.
Canonical (the company that sponsors Ubuntu) provides paid-for support, but it is in no way required. You'll find much help for beginners at the Ubuntu forums.
It sounds like this is the first time you're looking into open-source software (OSS) more than just "oh hey, I don't have to pay for this." While there is an abundance of freeware for Windows, OSS is a bit different in that the freedom we enjoy so much is not in avoiding having to put down money, but rather to change the code as we see fit. WeBWorK, for instance, is open-sourced; if something's not working how you like, you can dig around and hack up a solution.
The point that I was originally trying to make (I think) was that Canonical simply provides precompiled (and possibly patched) versions of software developed by others. If they decided all of a sudden to stop releasing updates, you would still be able to get the software from its original source (the author) and install it.
As a general rule of thumb, Linux and its cousins are much cheaper to use than Microsoft solutions - if you have time to spend instead of money.