Cameras: if you plan on becoming a professional, I'd say start with either Canon, Nikon or Sony, as currently, they're the top 3 brands. Pentax are good too, but they only offer APS-C cameras, which you might not like as a pro. Get an entry level SLR from either Canon, Nikon or Sony and a kit lens. They're all equally as good, it all comes down to what feels good in your hands, but if you have photographer friends/relatives/etc... get the brand they have, that way you'll be able to use their equipment and such. No point in getting expensive equipment and lenses when you don't know much about them. Buy new stuff as you outgrow your equipment, that way you'll know what you're looking for in a body or lens.
Getting better: Read and watch a lot of photography related stuff, and then practice them. A lot. And then experiment and try new things yourself. No point in practicing when you don't know what is it you're supposed to practice. First things to learn should be the exposure triangle (shutter speed, aperture and ISO), and how it affects your image, and basic guidelines of composition.
Photography classes: They're good in that they teach you the basics, and you'll have someone who you could ask if you don't understand something (of course, you could always ask here as well, plenty of knowledgeable and helpful photographers here), but the best thing in photography classes imo is that there's someone who'll critique your work. Honest helpful critiques are rare online.
Becoming pro: Get into a few good marketing and business running classes, cause that's what you'll be doing most of the time as a pro, marketing yourself.