Device tree GPIO understanding

Please look at the following code .dts

How can I access/control the keys KEY_RESTART, KEY_WLAN, KEY_WPS_BUTTON from usermode?
What is the difference between
53 leds {
68 &leds {

This may help

53 leds {
This node use the gpio-leds kernel module, the LED is managed using the gpio functionallity

68 &leds {
In this node we have hardware controlled LEDs, using a different driver, managed as "pure leds". Or controlling a serial LED IC like a 74HC164D.

They both could be managed with the gpio-leds kernel module if not connected to a serial LED IC controller. Using the hardware control LED driver where possible is more efficient. As a result of this, you have two different nodes for LEDs