The top circuit is incorrect, pushing any button will set all the input pins to HIGH. The second is correct, however I would use much lower resistor values from say 10k to 50k ohms. However the simplest method to wire up buttons is to turn on the internal pull-up resistors in your sketch software for each pin you are using and wire a ground to the other side of each of the switches. So in your sketch, reading a LOW means that button is being pressed and reading a HIGH means it's not being pressed. That way you need no external resistors and just one common ground wire to one side of all the buttons and of course one wire each between each button and it's arduino digital input pin. That should clean up your external wiring some.
PS: your switches are not being wired in series, they create four independent parallel paths for the four input pins. You just are taking advantage of the fact that those switches have additional terminals that are wired together to allow you to daisy chain either a +5vdc or a ground bus on one side for ease of wiring.
Lefty