AvatarPeer Marschel

Are you doing your external rotation exercises below and above 90 degrees along with your empty can exercises? I would think strengthening the rotator cuff would help alleviate some of the excess translation causes some of these issues. 

As for the popping and cracking, I use the Gemini with many of my athletes (mainly high performance tennis players.) But for some it is a bit to painful, so I suggest a lax ball or peanut set up. 
Then obviously make sure you have full internal and external rotation (ROM) this can be achieved by some simple PNF stretching.
K Star has almost all of this stuff on his site, but if you want to check out the band exercises I am talking about check my website (www.gtsgermany.com) and just click on the youtube or FB link.
Good luck man!