I have 4 skinned Behringers in my console. When I first connected them up, your Problem 1 appeared. The builder of my keyboard stack had removed the buttons, sliders and faders because I am using a different MIDI input for pistons. He retained one slider at my request and mounted it in the bass keyslip of the lowest keyboard. Fortunately he hadn't discarded the leftovers. I retrieved the other buttons, sliders and faders and reinstated them. They now lie hidden away inside, doing absolutely nothing other than restoring normality. It seems that it's necessary to keep all the original circuitry intact in the Behringer keyboards, even if some of the controls aren't to be used in a skinned installation.
Regarding your Problem 2, I'm afraid I can't shed any light on this one. I've never experienced anything like it myself. You could try performing a factory reset on the keyboards in case some errant control code change has somehow crept into the system. The user guide which came with the keyboards will explain how to do this.
Andrew