Subsequential edits within five minutes of the initial edit are combined into that edit. So if you post a question or answer, and then read it after posting (which for some reason may involve a different state of mind than while editing) and find a mistake, then go ahead and fix it within these five minutes. Of course, the question will get bumped to the front page on the first edit already, so be careful not to post something seriously incomplete because people may downvote that while you are still editing.
If you have something substantial to add to a post, or found some serious mistake, go ahead and fix it. The same goes for language mistakes which might make reading harder. But while you are at it, read the post carefully and try to fix all mistakes in one go, so you don't have to edit again for each subsequent mistake you find. (It would be fine again if you found all of them within five minutes, though.)
Does this bump the question
Yes it does; an edited post will appear on the front page. Which also means someone may take a closer look at what you are doing. As the saying goes, never show fools unfinished work, so make sure you save only when you are ready.
and also alert the OP that a change has been made,
If you edit an answer of your own, the original poster of the question will not get notified, as far as I know. If you want them notified of some substantial change, write a comment as well. When editing a post from someone else, the original poster of that post (question or answer) will get notified.
and if so is this really annoying for them!?
Depends on reason for edit and frequency of edit. If a post of mine were edited for grammar five weeks in a row, I'd be annoyed. If the same post were edited to improve formulas, add illustrations, and fix language, all in a single day, then I'd likely only look at the edited question once, and I'd also consider each edit a worthy contribution.
Also are my edits stored, and if so are they publicly visible, and how can I see how many edits I've made??
The text “edited (by …) on …” below each post that has been edited is in fact a link to the revision history. There all the edits made to the post are publicly accessible. Edits occurring within five minutes will get bunched into one, though.
If you want to see all your edits, go to the the list of revisions in the activity tab of your profile. If you want to be able to tweak how this info gets displayed, the Data Explorer may be of some use, e.g. using this query I just wrote or one of those mentioned in Is it possible to see a list of all my edits using a query?. Note however that the data used for this is not perfectly up to date, so the main point here is finding older edits. This again demonstrates that all your activity is public in some sense.
I read that ten edits and your answer becomes Community-Wiki, which is some kind of limbo-land?
This is no longer the case, at least not automatically. And Community-Wiki is not limbo, it just means you won't get any reputation for the post any more.
it took four attempts to format things properly
There should be a live preview of the post below the edit box. So I see no urgent reason to save anything just to see what it looks like with formatting. If the live preview doesn't work for you, or displays things different from what the saved version will look like, that sounds like a bug to be reported, investigated and fixed. Comments suggested using the sandbox to prepare edits, but with the preview in place I rarely see the use unless you're switching between devices or something like that.