p8ntballer app

[T7ank]

Forum runs on XenForo forum software which is not open source. So in most cases every moddification to would be payable (IMO).
There is always an option to turn on email notification about received messages and new posts in subscribed threads.

EDIT:
http://p8ntballer-forums.com/account/preferences

 

[Harbinger]

Tapatalk would be a good one to have, if you don't have 4G at the time the site can take a while due to ads etc, Tapatalk works well even on G and E, plus makes browsing posts / threads and notification a whizz.