I'll make it brief.

I feel smalled CC bikes such as the Kawi Ninja 250 help a rider develop their skills much better than will a 600+ sportbike.

You need to get to the point where a small bike will do anything you want on it before you move to a 600.

That is the way i would do it. Your first car shouldn't be a 500hp+ car so a sport bike shouldn't be a first bike.

One more thing. I am under the impression that an accident is not unlikely so getting a new bike with expensive fairings and bits is also a bad idea.

Get something cheap just in case you drop it.