In casual conversation and posting, I'm a little more lenient on myself. For instance, I'll sometimes make a post using consecutive prepositions even though that's incorrect just because thinking about the proper correction would take too much time.
In my fiction, however, I won't stand for such errors (except in the speech of my characters). My only exception is the use of "..." to end sentences in WotF, when it really should be "...." in that case. I didn't realize that until after having used it incorrectly countless times, so to maintain consistency I've continued omitting that last period. Maybe someday I'll go back through all my previous pages and redo them.
As for having that "Last edited by" message, it doesn't appear unless you make your edit two minutes or more after submitting the post.