Marlin questions

I am attempting to use marlin towards a 3D printer I am constructing however, I had a question about it.

First off, this may be a newbie question, but I am not using an SD Card Reader so if I delete every file dealing withe LCD Display and the SD Cards I won't have any problems, right? Besides dealing with deleting any imports and such.
Would it be easier just to leave all the files in there? Or would it effectively make the sketch size smaller so the arduino would run a little faster.

The way the code is written, if you have your configuration.h setup properly, the code you wont be using is IFDEF'ed out. This means that it does not take up any space in the resulting hex file that is uploaded to the Arduino.

It's probably not 100%, but I think you'd be asking for trouble if you start deleting files.