Vag - Reconsider starting with a dirt bike. Not a motocross bike, but rather a trail bike, perhaps in the 200-250cc range, as your first bike. Something that can be ridden on the street and trails so you can venture out onto the street eventually, but spend a lot of time learning on the trails. Reason? Several, but here's a few...
1. You can learn more riding a trail bike in the dirt in a month, than you'll learn on the street bike in a year.
2. Falling (which probably will happen!) is a lot less painful in the dirt than on the street. And chances are you'll get up and walk again on the trails - all bets are off if you fall in the street.
3. You'll be able to push your limits and boost your skill and confidence level much quicker on the trail bike.
4. Trail bikes are fairly easily repaired if you fall. If you fall on a sport bike (even a SV650), be ready to dig deep into your pockets.
5. A trail bike will cost less to purchase and insure.
6.. Most importantly, the skills you'll learn riding a trail bike (in the dirt) could end up saving your life someday when you graduate to faster bikes.
How safe is riding a bike? As safe as you want to make it. Most accidents are avoidable, IF you drive defensively and have the skills and knowledge to make the right move, at the right time when problems pop up. Unfortunately, right now you don't have knowledge or skill. That's another reason to start small, and work your way up. Start with something that is fairly easy to control. Motorcycle Safety Courses utilize 125cc and 250cc bikes in their schools because they are "easy to control." Larger, more powerful bikes sometimes are not.
We had a lot of amazing 17 year old car drivers in our neighborhood too. But amazing as they were (and I'm sure they all thought they were!), some of them didn't live to see 18. Don't let your confidence overtake your skill level.
The 650 and 750 models you mentioned can easily kill someone that's new to riding - very quickly. They will exceed 100mph fairly quickly, and even these bikes are probably faster than any car you've ever driven. Add to that cars and trucks buzzing all around you, and most of them having a tough time seeing motorcycles, plus you're in a whole new learning environment with very little riding skills..., you can see how it could add up to a dangerous mix.
My wife rides a Kawasaki Z750. It's a fairly quick bike (about 80hp), and can reach 100mph fairly quickly. My wife has been riding for 20 years. She taught herself to ride in the dirt. No way I'd hand the keys over to someone that's new. That's just not smart.
Do yourself a favor, learn in the dirt and you'll have a better chance of making it to that University!