Need Linux USB/HID interface libraries and the examples in C/C++ or PHP

I have a device(FINCH robot) the shows up as a

/dev/usb/hiddev0

on ubuntu linux. The device seems work correctly using Java software provided by the device vendor, without any modifition on the Linux/JDK or whatever.

I need to write my own code to drive the device, with either PHP or C/C++.
I had assumed it was simply a USB/Serial device and trying to implement the commands listed at this site:

http://www.finchrobot.com/usb-protocol

, apparently with no success, until someone from the vendor told me it is an HID device, not a serial. Their Java code works on top of a C++ HID library, as I was told.

Now I need two things: 1) a quick education on Linux/USB/HID, to the level just being able to understand how to send these simple serial-like commands and received responses (reports in HID).

 2) C/C++ interface libraries on Linux (uBuntu) for HID devices. With sample codes that include  "/dev/usb/hiddev0"  file desciptor, would be most appreciated. In fact I would rather write PHP code; if someone has a Linux/PHP/ HID code, that will be amazing.

Thanks in advance

ZZ