Does having a 401k mean I need more than just my W-2 for my taxes? Do I need to do anything else or am I good to go?

If you are currently investing in a 401k through your work all you need is your W-2 for that, the 401k information will be reported on your W-2. As you go through the program, it will ask you certain questions, some will pertain to you and some won't, enter in the information you have and you will be all set. 

You only report the 401K contributions from your W2, nowhere else.
If you took a withdrawal or transferred it to a IRA Account you will get a 1099R to report.