How much posting is too much?
There's no such thing as too much, really. It's nice to make use of linking to other threads; for example, if you've described a series of events in your life very specifically, you don't need to describe them again - you can link to the post with the information, and then carry on with what you mean to say. We generally try and avoid having threads get too chatty - too many one-liners in a row being traded between two members, and the topic gets lost. If you have a continuation of an event that you started posting about in one thread, post again to that thread if it makes sense to do so; helps readers down the line follow the continuity.
Well, I tend to write in blocks of 1400 words or so :bag: - everyone has their own style. Go with what feels right. And sometimes, it's fun to play around with being more direct (if you tend to apologize alot) or more descriptive (if people misunderstand you alot). From all your posts I've read, I'd say you are quite readable; I wouldn't worry.
Do these 'guidelines' apply to my 'Trauma Diary,' or is that mine-mine-mine ?
Yours, yours, yours. You can also request that other members not post in it; or, you can let people comment as they come along.
"Followers" scare the living snot out of me - even the word gets an adrenal response. What's it for, why is it here, how should I feel?
It keys into a few other functions. You can set your profile to be viewed only by people you follow, for example. You can set it to only accept messages from people you follow. You can use the people you follow to tailor your browsing experience, in the various tabs. It's really a tool for the follow-er, and as a follow-ee, it just means that those people are cool with you. But it's a great tool for restricting access to your account; if you don't want someone to PM you, just put your privacy settings to 'allow conversations from people I follow only', and then follow anyone you like - or no-one.
At what point does a (my) sincere attempt to help someone become smug self-promotion?
When you suggest they check out your blog, or read your book, or watch your you-tube, or follow you on twitter. Basically - trying to push your output, separate from this site, onto others. Recommendations of books, products, facilities, etc. are fine; that's resource sharing. Suggesting that someone go see your therapist because they give you a discount for referrals...advertising.
The last three things would be: try and use full terms, not acronyms; they don't always translate for a global readership, and they sometimes double up - Both Bipolar and Borderline Personality Disorder can be called BP. Suicidal Ideation and Self-injury, both SI.
PTSD is one we all understand - but if you've got the stomach for it, generally better to use the actual words.
And, we don't use trigger warnings, because everything would be a trigger warning.:) It's fair to say "I'm going to write some (graphic medical procedure), (abuse details), (whatever you might be worried about) out now", if you want to give a little warning. But it's really not necessary.
And - it's OK to disagree. Sometimes, challenging an assumption is the most helpful thing a peer can do. Without the broad range of voices and opinions, this place would just be a decade's worth of commiseration. It's OK to engage more than that. Sometimes there is conflict, but it's valuable as a way to practice things like not personalizing, not jumping to conclusions, just reading words, not jumping too fast to reading 'tone'. It's all good.