Hey, Newbie, and welcome to the World of Sportbikes. Guess that's why they call this website what they do.......
I was where you are a few years ago and faced with some of the same decisions you are now facing. I finally settled on a Yamaha YZF 600.....mild mannered enough if you lay off the "loud pedal (handle?)" but always willing to move on down the road at high velocities. It was something that I knew I could grow into. Sit on every bike you can, and find a model that is comfortable for you. Everybody is different.
As others have pointed out, don't go too small or underpowered, because the only thing you will learn how to ride is small, underpowered Sportbikes. Having said that, I can't reccommend anything much bigger than a 750 for a "first bike", since you may very well get easily frustrated just trying to hold the thing up at stop lights.
DEFINITELY take somebody knowledgeable with you to check out any used bikes you want to look at. Unless you know the complete history of sportbikes, or even a particular model, you could get easily burned on a purchase you are stuck with and won't be able to get your money back out of, if you don't like it. I'm sure others have horror stories they can tell.
I can't speak from experience on the MSF course, but everyone I ride with raves about it as a great confidence builder.
Lastly, we are all interested in your progress, so please let us know how you're doing.
"After all, we ARE professionals, here."