No you cant, but this may be added in near future.
Add subscribe widget to AP Tag page and thats all.
In that theme I just provided styles for Q&A and Buddypress. If you want you can style blog posts.
Please update category and tags extensions
Widget already exists, AP Users widget. You can show a list of users sorting by reputation.
Hello, Site activity and Notification system will work with Buddypress or it is the own function of Anspress? I mean will I get problems if I use Anspress and Buddypress together?