SOS----USB Driver

1. In an Interface desdriptor, If there are a Input pipe
and a Output pipe (without regard to Interrupt or Bulk
endpoint). From the use-mode point of view, how do you know
when the data is available to read and when writen data is
done? Why I WriteFile to Output pipe and then ReadFile from
the Input pipe is not correct?

2. I have bought USB device(Host-to-Host Cable) from the
Market with the enclosed software(Driver and Application)
for test, and I have writen another USB driver for this
device and simple testing application. After I install the
device with my driver, there are two GUID in
HKLM\System\CurrentControl\Control\DeviceClasses Entries,
one is the generated by myself, other is same as the
original one, Why?