Allow resubmission of same image after digitial processing
Related forum thread (larger uploads) http://www.geograph.org.uk/discuss/index.php?&action=vthread&forum=12&topic=11368
This is not easy to implement. Dont know when it might be added.
I think I did a substitution of this sort without comment. The poor-quality original was rejected at my request and I uploaded a somewhat better-quality image of the same view.
It can, but its a lot of work. As you your second question, I would suggest almost none. If you have another photo, just add it, no need to remove the other.
can it be done? Or alternatively, what's the possibility of removing an image if one has a similar but better one?