Is there a newsletter with the best questions/answers on the week for a specific group
Yes, every site has the ability to subscribe to the newsletter. You will receive the hot questions of that week (which is the closest to 'best' you get). You can manage your subscription settings from your network profilefrom your network profile.
Can I specify some tags to receive only the best questions/answers with this tag?
Yes and no. There is just one newsletter. But you can subscribe to receive notifications of activity in a specific tag too if you want to. You can do that from the filtered questions pagefiltered questions page. You can define your filter as you think it includes the best questions.
