Where is the documentation?

I'm trying to get into computercraft, i got the direwolf20 1.7.1 modpack, with Peripherals++ and Openperipheral. I would say that i'm fairly experienced with programming, but i've a hard time finding the documentation, for the peripherals… I know that peripherals++ got a website with the main functions, but not the return values. Then with openperipheral it's even harder, what i have done is using the autocomplete function in the advance computer in lua mode. Is there easy way to find the documentation for all functions, and their returned values?

ComputerCraft's own peripherals are documented here.

Most peripheral mods are pretty good about documenting things on their website. OpenPeripherals has been a bit of an exception, though these days, you can get some excellent documentation for it by typing /op_dump into chat while in single-player. This'll generate an xhtml file in your game folder specific to your modpack.

I can answer some of your concerns.

To get a list of all the callable methods on a peripheral you can call peripheral.getMethods()

For other things available via the peripheral API (and plenty of other good info) take a look at the ComputerCraft Wiki

For OpenPeripheral there is built in documentation with each version. At the command prompt simply type openp/docs [side].
EDIT: Bomb Bloke didn't mention this, so this may not longer work

I've not played with Peripherals++ so I'm no help there.

EDIT: :ph34r:/> 'd