A Job? For me?

I was scanning the classifieds today, which I haven't done in a few weeks, and I saw what I've been searching for for over a year!!!  There's an ad for a vet assistant/receptionist!!!!!  I really want this job.  I'm so perfect for it!!!!  Now of course, I'm going through the doubts in my head, What should I wear, do I need to look dressy, or would it look better if I appeared a little relaxed? How would it be best to answer this question or that question? Should I call them after I put in my application or will that just be annoying or will it seem like I'm really interested in the job and should be given an interview?  How can something that seems so good, make you feel so sick?!?!?!  Ugh, I need a nap!  LOL