I want to start out with that I completely understand how scary this is. It's new and feels invasive and it's confusing and it can really suck sometimes. I want you to know it will get better, you will get used to it and figure it out.
As for your questions, I've personally never heard of internalized DID-phobia but as a gay autistic trans man I do have some internalized homophobia, transphobia, and ableism. What I do to stop that is remind myself: that is wrong. Thinking bad things about others because I am insecure is wrong. I try to identify the behavior and shut it down.
I dissociate a lot, multiple times a day, but we switch a lot less. The best way to tell if you have switched is to evaluate how you felt before and how you feel now. If you feel generally the same, probably haven't switched. If you feel a different emotion that you'd think you have no reason to feel or your sort of attitude and thoughts and tendencies change, probably switched.
I can't really access our innerworld, so I can't offer a lot of advice on that question, but I know the app SimplyPlural that we use to track alters and who's fronting has some helpful links and one of them is about innerworlds.
Hm, I struggle with the communication to, like, "Is this another alter or just me?" The way I figure it out is specifically think about that other alter that I think I'm talking to because I guess it kind of like, summons them? I don't know, but then if I feel they aren't close to front at all then I'm like "oh, that was just me" but usually they're like "yeah that was me". If you don't know if it's a specific alter, my suggestion would be to record the interaction, like write it down somewhere
I'm so sorry you feel this way. I've been there, it's not fun. I don't have an exact answer for you. This disorder has a lot of ups and downs. It sucks. I do think that with time and effort you will start to feel better, as you learn about the other alters and buikd communication and such
You can always DM us if you need someone. We wish you the best <3 ‐Cody