I don't think there is a right or wrong here. I just know that I'd probably do what your buddy says he would do. That's just my nature.
Both are wrong.
Turn it back on her in a playful way, not in a dickhole way that admits defeat and takes it out on her.
Something like "I don't know, we just met and you could be a total creeper. First you have my number, then you are chasing me down. A man must make sure he is safe". All done with a shit eating, sheepish, boyish grin.
How she replies to that tells you if you have a chance while telling her that you can be a bit of fun.
DD anyone? No not Dungeons and Dragons.
This is the correct response. I have used similar responses before three or four times, it's good fun, if you make her laugh, you feel great even if she never calls. It shows her you can take rejection (if she is rejecting you) and it shows her that you're funny and interesting (if she is on the fence, or really doesn't make a habit of giving out her number to complete strangers she met five minutes ago).
I don't know. I've never taken a girls number. I've always given mine out.
I would take my chances and give her my number. Because as you say, she might call. By giving her your number you have nothing to lose and everything to gain.
Wait twenty years.
You'll look back laughing you even had such things to argue about.