Yeah, while I do enjoy the game $4.99 for a new song and level skin is too much $1/$2 at the most would be a fair price...
Pre-empting Adult Swim support to say they just released an update which resolves iPhone 6/6+ control issues.
I believe the way it works now (or should) is that interstitial ads (except cross-promotion) are turned off when you make a single purchase. What ad is it that you want to turn off?