I like all of this apart from the "edit everyone's posts together" and "no posting heroes" parts. It makes the action [i]extremely[/i] non-interactive, as none of the players are working together, or have any idea what the other heroes are even doing, even if it's the sort of thing that they'd actually be able to see going on. On top of that, it's not a very good way to mask who's who: it becomes a case of 'mask the writing style'.

And no-one having any idea what any other character can do sounds like a grand way to have too much overlap and/or no idea of what the overall group is turning out like.

If it's your first time GMing, requiring a mass-editing session and having everyone wait on PM's they can't see or know about is going to make things much, much harder.