If you are calling to the same delegate with multiple extensions, how do you order one above the other? For example BBInsert Bar, below Discussion tags? Sorry in advance if I'm asking this in the wrong context.

Depends which extension you enable first. They are loaded in the order on first activated if I recall correctly. Just look at your conf/extensions.php file. I don't think there is a way to set priorities on delegates.

Could this functionality be added? Where the AddToDelegate function would have an extra parameter, $Position, like the AddRenderControl function in the Page class.