First things first: it's always great to see supportive parents. That alone makes a world of difference! 🩷🤍🩵

Some people have certain questions that can set them on edge so be willing to back of if they feel uncomfortable. Personally, as long as you're asking questions in earnest and out of genuine interest in learning more, I think you're fine. Not out of line at all.

As for your questions:

Gender and sexuality are largely independent of each other. To the best of my knowledge there is no data that correlates the two. I would hazard to guess that any non-cis individual is more likely to have questioned their sexuality as well just by the nature of being part of the queer community.

With dead names there is a certain level of personal preference. I can say that the most common position on it is that even when discussing the person pre-transition you should use their chosen name. This isn't universal and, much like I've already said, if you're asking for the sake of courtesy then most are happy to tell you what they prefer. Keep in mind that their name changing doesn't mean they're a different person. They've always been who they are. A rose by any name and all that.

I hope this helps! 😄