Greetings.
Some very good tips posted. For what it's worth Photoshop is the industry standard, but most of it the average person won't use. Photoshop Elements (if it still exists) has pretty much all of what anybody would use. Most free editors are useful and free. Elements used to be ~$100 bucks and even old versions likely do more than you need.
IMO the best of the open source ones (=free) are:
1) GIMP
GIMP - The GNU Image Manipulation Program Kind a goofy to learn, but it works. When you get the hang of it, it's pretty much as good as Photoshop.
2) Rawtherapee
RawTherapee Blog Better than Photoshop RAW editor in many ways. Will do JPEGS etc. as well as RAW. Have used it for years and have tried virtually every one out there. Non destructive years before photoshop was.
For cameras and photo tips:
Ken Rockwell
KenRockwell.com: Photography, Cameras and Taking Better Pictures Really a weird guy, but the most comprehensive reviewer of "Stuff" out there. Takes a lot of heat from the community, but there is more advice there than anyone can ask for. You kinda have to dig through his site. His principles of how to take photos are founded on basics and you can use them with confidence. Don't need to like him or his style; good stuff there.
Hope this helps
r