I'm with Uncy Bob on this one. It's only 2 stroke poppers that blow up around 20K, cos they need thrashing to work properly.
You've gotta 4 stroke. My first big bike was a GPz 750. I bought it with 58,000 on the clock and put another 25,000 on it and sold it 6 years ago. I still see the bike around - so no worries on that score. Regular oil changes is the secret.
When it comes to safety, a helmet is a must. Secondly, but just as important is gloves. Get the best you can afford, make sure they fit well, though they do take some wearing in. Hitting tarmac with bare hands is soooo painful and with your hands bandaged up - you virtually useless.
Welcome, this is the start of a new way of life.