As someone who used to see myself as cis bisexual (before I was comfortable with accepting my trans status), I can definitely relate to #1 and #2 in this post. I gained a lot of privilege when I was with a man that I lost when I was with a woman.
Having been on both sides of the fence, and even on top of it from time to time, I can say that #3 is really missing the point of what "privilege" means. I wish privilege were a feeling! Unfortunately, privilege is an systematic advantage gained by having a status ascribed to oneself.
If people think I'm cis, and they see me with my partner, they will treat us like we're straight. It will not feel comfortable, and in fact will feel very degendering, but that doesn't change the fact that even wrongly-ascribed privilege is still privilege.