To the third DINx4 module (since it's only 5 additional buttons you don't need a full DINx4, a DINx1 with only one shift register will do) If you aren't scared of following the instructions here , you can connect the buttons wherever you want to and change the pin assignment in the software. You'll have to a part of it anyways as 5 buttons (2x20) is the default option. Detented ones (with the "clicks") are usually used for the menu encoder, while undetented ones are used for all the other encoders. I personally like detented encoders more so I used them everywhere - it's really a matter of taste. Yes and no. It's a regular DIN module, but not a fully stuffed DINx4 with 4 shift regusters as you only need one more.