addressing emails >.< Options

[batman]

I'm pretty clueless about email communication, especially if it's with a professor, employer, prospective employer, etc.

Got an email from a medical center wanting to set up an interview after reviewing my app/resume ( ). If he introduces himself as "John Smith" and addresses the email as "Dear Melissa," do I write:

Dear John,
I'll be available for an interview on ____ before ___pm.
Thanks,
Melissa

or

Hi John!
I'll be available for an interview etc etc etc.
Thanks,
Melissa

or

Dear Mr. Smith,
I'll be available for interview etc etc.
Thanks,
Melissa

And should I write more in the body paragraph? Like "I look forward to speaking with you" or "Thanks for your interest" or w/e?

yeah, I really, really, really want this position and I'm freaking out a little bit.

[superstitious]

"Thanks," seems too informal. "Thank you, <name>" would be better, in my opinion. Also, it typically a good idea to say something along the lines of "I look forward to meeting with you." It just shows that you are really interesting in a position without sounding desperate.

Also, call back to thank them for the interview later that afternoon or the next morning. It's always a nice touch.