1- Try to see if you can get Video if you remember the date. You will need to speak with security. Most likely they wouldn't give it to you i bet, if you know a cop around here and ask him to go get it for you, they will give it to him.
2- I wouldn't deny the whole thing at all. It would just make it seem like you are hiding something since the *** will know your face and got your License plate. You probably would still be fine but it's just safer not to deny it.
3- What i would do is try to find a good Lawyer, And just be straight up at the court. Reading what you wrote you did nothing bad. You got out of your vehicle and helped him get to his feet and he was the one being dumb & skiing in a parking lot. You should of been the one freaking out for hitting your car once you know he was ok. It would of been bad if you just drove off. There is nothing you did wrong so just tell the court you were leaving Brighton Parking lot approximately 10MPH keeping your eyes towards where you were headed, then some guy out of no where hits your car and you got out to help him. If the guy wanted to sued you for some dumb reason he should have called the cops and made a report. Been too long for the guy to do something about this. I'm sure you will be fine bro, Good luck!!