The idea of an edit function has been discussed many times. What appears seems to be what we type so the best way is to read your post through before submitting. You can drag the corner of the answer box down so you can see the whole post in one pane.
Even a two minute window seems too much at busy times as sometimes more than half a dozen responses can come in within that time, and then people may need to edit their replies and that just has aknock on effect and can make the thread look odd.
If a post needs to be edited why not just copy it, make an amendment (pehaps using italics for changes) and then repost it as a reply.
I don't really have aview on the save to come back- i would just leave the answer there and not press submit, or I'd put it on my clipboard, but I probably wouldn't use it if by the time I got back others had replied and mine seemed to add nothing by that stage