When it comes to editing software, it seems that Adobe Photoshop is the most used software in the industry. As a cheaper alternative, I found mention of Adobe Photoshop Elements, which although lacking some features, such as video editing. Another similarly priced package is the ACDsee Pro 7. These are noted in one article as the three best professional programs for editing.
However, there are other options for purchase, which I will investigate more into. But I also know of a few open-source alternatives, but I haven’t actually used these programs yet. So I can imagine there would be a learning curve. There is GIMP which is essentially the open-source version of Photoshop. Then there is Inkscape as an open-source alternative to Illustrator, which works with vector images. There are definitely other options out there, but these are a couple that I have some familiarity with, and have been recommended by friends.