Set up a regular forum for discussing issues, rules etc.
Have you thought about the possibility to set up a regular forum, so people can interact more directly about different issues? Also, it can be useful to discuss some rules that we can follow. For example, I am thinking to come up with some naming convention for standarize the name of the products. For example the same product can appear as cous-cous, cus-cus, cuscús, ..., tahine, tahin, tajín, ... The searching engine won't return you the correct items if every product is named with a different spelling. (suggestion from Javichu)

-
So we have the uservoice forum http://openfoodfacts.uservoice.com/ where I have moved your question. :-)
It's supposed to be for Ideas, but we can use it for Questions / Issues as well. I added all your questions on it, with (question) at the end of the title.
I'm also open to try and/or create other channels. For the French version, we use a Facebook group a lot for keeping ourselves updated about news. But it's not very good for deep discussion as it's quite difficult to find old discussions. We also have a mailing list, but it is not very active. And there is a blog with comments: http://fr.blog.openfoodfacts.org
What I can do is to create a blog and a mailing list for English too (and possibly other languages as well if there are several motivated contributors)