Disclaimer: I am not a Medical Transcriptionist, I'm a techie software gal, but I worked in the transcription world for 8 years (right up until Nov. last year)... here's what I know:
MTs get paid by the line they type. The best yearly take I've seen is a senior QA person who picked up a TON of overtime and cleared 60k in one year. She's been an MT for like 23 years, this is not common cash, and she types very highly specialized reports at a stunningly rapid speed with her eyes practically closed. In other words, she's a rarity. **Most** MTs work a little less than 30 hrs a week, and make about 15-18k a year. If you do decide to persue this, be sure to go to a very reputable program, Career Step is a great one. That's the one most companies recruit out of.
I don't know that I would recommend someone persue this path right now though... the MT industry is changing rapidly, and the workers are suffering greatly for it. My former company just laid off 1500 MTs in favor of overseas production... another big player just laid off 2500... so yeah, it's a problem. For those that are hiring, shifts are becoming scarce with actual reports to type (translated: $ to be paid) fewer and fewer.
Yes, you'll most likely work from home, and no, there's not much you can do to enhance your postion from the starting gate. Once you're in the field for a while you can train into specailties, acute care, QA, and other things, but competition is hot for those jobs, so it's not a given... it's a lot of work. Definetly do your reasearch and make your own choices though... GL to you!!