Ask yourself if it's really necessary. If you see her a lot, maybe, but if you barely see her, it's not such a good idea. And, you'll have to make sure she'll be accepting, too. If you haven't came out to your friend yet, come out to them first, then ask for their support. In any case, good luck.
Not necessarily. If you feel comfortable confiding in her, and think that maybe she could be someone you could talk to, then it couldn't hurt. However, you shouldn't feel obligated. It's really none of her concern what your sexual orientation is.
I told my best friends Mom and she was amazing. I had known her for years and we spoke tons and she used to send me usual stuff and links to websites for support and help. She was amazing and it really helped me. If you have a close relationship with someone it can be such a benefit, an if you think you have that with your friends Mom then maybe it's a good idea. If not, find someone who you are close with and who can help support you
I think if you feel ready and you want to tell them then you should. I think maybe you should tell your friend first like someone else said or you could tell them at the same time. If you're close with your friends mom and you like her I think you should tell her but only if you want. I hope if you do that it goes well and they accept and support you. Good luck!!!