Hello. So at the top of configuration.h you should have serial port set to 1 and I like to uncomment second serial port and set it to -1.

For lcd12864 mode you will need to connect the 2 ribbon s to exp1 and exp2 and then at the bottom of configuration.h you will want to uncomment reprap_full_graphic_controller

For the touchscreen ode you will only need to connect 4 or 5 wires. They are +5v power, ground, rx, tx, and the optional 5th pin is for reset. This pin will trigger a reset on the mainboard when the reset button is pushed on the display. This is a nice option to have but as with the 2 ribbons and lcd12864 mode it is optional and the screen can function with just the power, ground, and communications wires connected.

I have all of my screens connected both ways and regularly flip back and forth between the two and I strongly recommend you do the same.