GArch..
1) RELAX.. being nervous will only queer the deal. If a woman or a man is nervous around me, I'd ask.. what's up with this? Being with someone nervous just isn't fun.
2) As for when to call.. 2-3 days after you get the number is a reasonable rule. Ice's reply is another reasonable rule. You don't want to call the next day, as it comes off as pushy and desperate. However, if she's into you, she'll be waiting for your call. A female friend of mine's told me that if she likes the guy, she'll be wondering.. will he call? when's he going to call? will he call? She gets bothered holding that too long, and emotionally will need to move on. If she's not into you, it really doesn't matter when you call...
3) RELAX
4) When you call her, act as if you've known her for years. How do you talk with your long time friends?
5) RELAX
6) When you decide what to do together, and get together, put aside the fact you find her attractive. Ask how you'd want this to go apart from the sexuality. Do you want to joke with people? Do you want in depth discussions about stimulating topics? Do you just want to hang? I'm not into opera, so I'd just tell her either no, or I might try it, but another time. What I usually do is pick out a handful of things I find fun doing. I then have her choose from these things, or come up with another idea. If she mentions something else, I'm not afraid to tell her I'm just not into that. If you go do something you hate doing, you'll just have a bad date.. you won't get anywhere with her then.
7) RELAX
8) Women really have no idea if they are hot or not, just like guys. She's not making it an issue, you shouldn't either. She's friendly towards you, so expect that to continue.
9) RELAX
Good luck, let us know how it goes...