Thanks to all for this incredible source!
I am very new to all this but want to make the jump after reading all this thread and others. I have just received Pro Micro clone but still need to get a few things. Eventually I plan to attempt rudder pedals with a number of additional buttons. However to learn the process I am starting slow. Step 1 is to make a simple box with 4 buttons a Pot and Encoder (the last 2 are just for learning as I have no plans for them yet). Step 2 will be to add another 16-20 buttons with either matrix or Shift Register 74HC165.

Some questions:
When I add the extra buttons in Step 2 do I need to do a re-set of board so that it adds them?
I know that a matrix needs Diodes like 1N4148. But I am getting mixed up with Shift registers. Some posts say no Diodes but example in the Wiki seems like it has some. For a Parallel In Serial out Shift Register is all I need the 2-3 IC's and a PCB?
What is best way to obtain a PCB for Shift Registers?

Thanks