I’m a tech, not a vet, but I feel qualified to answer most of your questions, and to tell you to scratch most of what gatopescado said.
Vet school is the same four years as med school, and in a lot of ways it’s a harder four years. All the stuff med students have to learn about humans, vet students have to learn about 8 or nine different species, plus vet students have to be competent surgeons by the end of their four years. Human doctors (in the US, anyway) are required to go through a residency to become fully licensed, which veterinarians are not, but they go through the same amount of actual school, and the price tag for the education is about the same. If you go to vet school, you can pretty much count on being $100K in debt when you get out, sometimes more.
When you do get out, how much money you’ll make depends on the area and what type of practice you’re going into. In both states I’ve lived in (KY and NC), new grads in general practice make $30,000-$40,000 a year, which is roughly what medical residents make. Emergency vets tend to make significantly more, because they work significantly crappier hours and tend to see significantly worse cases. After all, you don’t come to emergency room because you’re healthy. Of course, ER vets tend not to be salaried, so if they don’t see any patients, they don’t make any money. Veterinary specialists make a pretty fair chunk of change, but I don’t know actual numbers on that. It is, after all, gauche to ask one’s boss how much he makes. Let’s just say they’re certainly not toddling down the road to poorhouse. Your hours will also vary by the area and what type of practice you’re in.
Likewise, how competitive actual practice will be depends on the area. A new vet could move into my in-laws’ county and immediately be swamped with work, because it’s a seriously underserved area. Here in Greensboro, however, starting a new practice is significantly harder, because there are a lot more vets in the area. Getting into vet school, however, is always highly competitive. As in more competitive than med school. Remember, there are only 27 vet schools in the US and Canada, as opposed to the hundred and some med schools in the US alone. A lot of people spend years of their lives and ungodly amounts of money trying unsuccessfully to get into vet school, people with very high grades and test scores and years of practical experience in the field. I’m one of those people, and I currently work with a couple more.
The big things about vetinary medicine are that it’s not helping the cute, cuddly little kittens, and that it’s often as much treating the owner as the patient. Vet medicine is wrestling a 130-lb dog who wants to rip your face off so you can draw some blood or put in a catheter. It’s cutting off the cute little kitten’s head because state law requires it be tested for rabies. It’s being stepped on and kicked and bitten and scratched. It’s picking maggots and popping abcesses and cutting out necrotic tissue (and sometimes you have to do gross things.) It’s coming home covered in piss and shit and blood and vomit and pus and anal glands (your dogs will absolutely adore you on those days.) It’s holding the hands of owners who call every day to tell you Fido’s poop is a slightly different color and they think he needs to come in. It’s controlling your temper when people bring in an animal that’s nothing but skin and bones and insist that he just stopped eating this morning. It’s comforting owners who have lost a pet, or who are struggling with the decision to euthanize. It’s putting down treatable animals because the owners can’t afford the treatment. It’s dealing with owners accusing you of not caring about animals at all, because you can’t afford to treat their pet for free. (You get pretty inured to the other stuff pretty quickly, but the last three never get easier. When it gets easy to do those things, it’s time to find a new line of work.)
In general practice, there’s a lot of routine stuff to be done. You’ll wind up doing a lot of vaccines and worm checks and spays and dentals. You’ll also be seeing a lot of bizarre illnesses and injuries, and doing emergency surgeries and dealing with some spectacularly crazy people. (I mean full-on tinfoil hat types who think the people under their houses are poisoning their cats and want a full toxicology panel run, or who want advice on wrapping their pets in tin foil to protect them from the gamma rays the neighbors are shooting through the walls.)
Veterinary medicine is hard, dirty, gross, and mentally and emotionally draining, and absolutely wonderful. But it’s not for everybody. If it sounds like something you might be interested in, find a clinic or shelter where you can work or volunteer and get in there and get your hands dirty. That way you can see for yourself what it’s like and if it seems right for you.