Hi Peter, thanks for the questions; this is a reply to your original e-mail, so I might have missed some of the things brought up by other people.
1. As far as I see, the "buttons", as you call them -- I guess that you mean those "Upload photo" links visible on the lists on Wikipedia -- are not time-sensitive. To remove them from the lists would require some manual work (e.g. editing the template on every Wikipedia that uses them).
However, I don't think we need to do that at all; we can keep those buttons there, just making sure that pictures will not be uploaded to "our" categories after the end of the competition. Leaving the upload links on the lists could possibly lead people to upload more pictures during the year; I am aware that this might have a negative level on the number of pictures uploaded next year, but this isn't our goal, is it?
2. I am not sure what notice you have in mind; this is probably something that can only be done by the many national teams on their external websites or on the project pages on their respective Wikipedias.
3. I guess people would like to have at least a day or two of rest from Wiki Loves Monuments before starting to work on the results, you know :-))
4. I will be shutting off the campaigns sequentially, country by country, just as I did when enabling them in the first place; the exact schedule is available at https://commons.wikimedia.org/wiki/Commons:Wiki_Loves_Monuments_2012/Checklist.
There is no need to change the running campaigns that much, as the almost only thing that matters to us is to make sure that the late pictures don't land in our categories, and this is achieved automatically by the {{WLM-is-running}} template.
5. I am afraid that there isn't enough time to translate the phrase into all the languages, especially as there is only two days left. We /might/ create a thank-you banner, but this would also require some manual work from a great number of people, and I am not sure we have enough time.