Does K2 have a subscription facility for blogs? ie can K2 send an email notification when a new blog post is posted?

Hi. There is no such functionality in K2 however this is something that can be implemented easily with a K2 plugin. I am pretty sure that someone has already implemented something like that. Try to search at getk2.org/extend/ and extensions.joomla.org/extensions/extension-specific/k2-extensions .