[Serious] I'm researching stuttering and would like to know your experiences

[Serious] I'm researching stuttering and would like to know your experiences Hey all! For starters, I do not stutter. I'm in the early stages of developing my first novel, and I'm developing one of my characters to have a neurogenic stutter that resulted after a traumatic brain injury. They say write about what you know..... and of course I'm doing the complete opposite. I've skimmed through some of the recent threads here and one thing that is very apparent to me is that stuttering conditions can be challenging in so many different aspects of a person's life. My intent here is first to be respectful of each person who would like to comment with their experiences. With my character, I also want to be as authentic and respectful to the factual aspects of stuttering. I have met people with a stutter before, but most of my experiences are from Hollywood movies, and most recently from watching the new It movies. I'm not planning on winning any Pulitzer prizes with my writing, but if someone who has a stuttering condition happens to read the book, I want them to think "he got it all right!" and not "he clearly only watched one movie with a stuttering character." I guess all that being said I just had some questions specific to how the condition affects a person's speech individually - and I realize my questions here are going to sound pretty ignorant I'm sure, but I simply don't know and that's why I'm asking! Does stuttering affect everyone the same, and I mean does everyone who has a stutter have the same difficulty saying the same exact words? Is it the same syllables or like you see in the movies it tends to be s's and m's that a character trips over, or is it different for every person what words or syllables they will have trouble saying? How often does a stutter affect you? Is it rare and only during very stressful situations or is it constant? Do people that have developed stutters due to different circumstances, such as brain injury, stutter similarly to people who (I guess?) were born with the condition? Finally, I'm most curious about the act itself... What actually happens at the moment that a stutter starts? Does your mind just draw a blank? Is it like a tightening of the jaw that just locks up and prevents you from saying the word? Is it always the same word(s) that cause it or is it random words? If you know a stutter for a certain word is about to happen as you're speaking, can you just say a synonym instead and avoid the stutter? Wall of text, I know... I appreciate those of you who stuck around long enough to read it all! Again, my goal is that I just want to learn and be factual and respectful to the condition. Thank you in advance to anyone who feels like sharing their experiences here with me!