Some newbie question, more axis, gripper second hole


Hello everyone. I’m fairly new to this whole subject, so please excuse for silly questions. The first thing i would like to know, would it be possible to add more axis to this arm? I would like to teach the arm for painting, where the brush should stand in about 60 degree and not 90, but not always, so it should be dynamic.
My second question is about the gripper air input, i saw a video, whereby there was a tube running into the second hole as well, what is that good for? Stronger grip?


You can attach your own end-effector with servo builded in, and connected to Dobot arm, which can operate in additional dimensions.

I’m not sure what do you mean by this tube in second tube- could you share a link?