thank you for your application. Regarding occasional progress on mythic bosses, I should inform you that we only did mythic in the past when we had enough people interested in it. While mythic runs did happen, they are quite rare for us and considered a bonus.
Also, we are currently on a raid break until 9.2. Activity in guild will increase again near release date of the next patch.
If you still want to join, contact Irya#2311 on bnet or whisper Irya or Xantyr for an invite ingame.