Serial output from arduino to php(localhost, usb port connection)

Maybe you'll have to put a capacitor between the reset and he GND. Because when the Arduino receive some incoming information (RX), it might thought that you are trying to download a ew program in it. It occurs to me when i tried to connect my arduino UNO to a RaspberryPi.

To communicate, PHP-Serial, like said Chagrin, is the best and easier solution to your problem.