Do the trackday!!...It's the very best investment you can make. Ride the bike stock....being a newish rider, you will NOT outride the bike, but you WILL learn invaluable amounts of skill and knowledge...You will learn all about the bike's ability, you're true riding ability, etc. The knowledge you learn will equate DIRECTLY to your road riding skills which could save your life at some point. It's funny cause I still look back at the very first pic I bought from my first trackday and laugh....I remember seeing the photographer and saying, I'm really going to lean over for a good pic...When I got the pic, I was still nearly up and down, but almost pooped my pants cause I thought I was going to scrape hard parts....lol
The trackday org I work for is more of a school than just 'get on the track and ride'. They have classroom sessions after each session you go out on the track. You talk specifically about what you just learned, your mistakes, how to correct them, and then get to go put it to use again. They have body position seminars at least once a day in between sessions. They will even take you out one on one if you are having difficulty with a specific corner or skill (like getting on the throttle at the apex)...
As for gear, go onto the org's webpage or forum and ask to borrow. Most people would be ecstatic to have someone new at the track....our org is truly a family. You can go up to anyone and ask for anything and they will be glad to help....Also, like someone else said, being in the novice group, my org allows textile. I've crashed in textile before on the street and luckily got 0 bumps or bruises. They prefer to have them zip together, but as long as no skin is showing, they'll let you ride in Novice.
Lastly, just use your head when you're out there. The track is the safest place to learn. No cars, no cops, no sticks, leaves or sand on the ground - only you and smooth pavement. Use the time to learn and not just go as fast as you can. Respect the bike and use your right hand wisely and the chances of falling over almost diminishes. But again, what you learn could easily save your life.