Yup, welcome to AA.
The guide starquest mentioned is great. We're big advocates of fishless cycling here at AA. The smaller tank used as a large filter is called a sump. It houses all your devices out of sight etc while adding water volume to your system.
If you're going to petco/petsmart as your LFS
, make sure to do your research before and after their recommendations. I have yet to find knowledgeable staff at these locations that cared more about my tanks than trying to make a sale. Hopefully the stores at your location have helpful folks; but just becareful.
Feel free to ask any questions you may have here. Folks here at AA are pretty nice and willing to help each other out.