We really don't have any low-level API documentation. It's rarely been asked for. Also, until the 6.0 release, the API was much more fluid than we would have liked anyways. It's pretty settled now, and we don't anticipate huge changes in the future because we now are able to add new social networks with (relative) ease as well as all the other features we want.
I can give a quick primer of what you're likely looking to do below:
In the JFBConnect -> Configuration -> LinkedIn area, add "r_network" to the Additional required permissions. That will let you access the user's 1st degree connection information.
Then, for code to fetch that:
$linkedInUserId = JFBCFactory::provider('linkedin')->getProviderUserId();
$fields = array('first-name', 'last-name');
$profile = JFBCFactory::provider('linkedin')->profile->fetchProfile($linkedInUserId . '/connections', $fields);
$connections = $profile->get('values');
foreach ($connections as $c)
echo $c->firstName . " " . $c->lastName . "<br/>";You can view the
LinkedIn Connections API Documentation
for all of the fields you can fetch about the connections.
Hopefully that will help you get started with fetching the LinkedIn info. Facebook friend information is much more limited as you can't fetch all of a user's friends. We can help clarify what you can get from Facebook if you need though.
Obviously, that's just connections, but it also points you through a couple of easy calls you can do.
The code above was tested, so it should just work (with a little luck). Of course, if you have any questions, just let me know!
Thanks,
Alex