Elements is a good start on Photoshop. Lightroom has its place too. It depends on what you want to do. Both will level and crop.
Elements has a stripped version of Adobe Camera Raw and Photoshop.
Lightroom has the same Adobe Camera Raw engine as Photoshop, but it is a browser which also lets you do some simple editing and printing.
Adobe Camera Raw has quite a bit of power. It is designed to work with raw files but it will also work with JPEG files. The full version has a lot of useful tools.
If you want powerful free software, look into GIMP.