I really never even considered telling people that I stutter directly (without them finding out on their own) until my therapist brought it up as a technique to help reduce stress. It doesn't necessarily work for me because I am not nervous about them realizing I have a stutter. I am more nervous after they know and I want to control it much more. From my very brief experience in the workplace higher management doesn't care that you stutter but rather that you are good at your job and help improve the company. As for presentations I can have a hard time and I always get very embarrassed when performing them, especially to people that I know. I find that if I just have to talk in a meeting in front of a lot of people I don't know that I do just fine with a few brief hiccups, going slow and steady definitely helps a lot. As for telling the girl you stutter I would just be super casual about it and just say something like "I don't know if you noticed over the phone the other day that I sometimes stutter, but I just wanted to tell you to clear up any questions you had about it." Or you could just go on without telling her. That's what I do, if they are curious then asking me is fine too but if not then I think they will realize that I do and they can respond however they wish to. I think that if the girl is shallow enough to not like you because of it, then she isn't worth it in the first place. Just my 2 cents though.