Airspeed Prime here with some Korra info.

So Much information from one picture!

We see Kya and Bumi’s faces, Kya is a Waterbender and Bumi a Non Bender, they appear to have no kids (though that may just be because they are not important characters and space)
Korra’s parents are called Senna (Mom) and Tonraq (Dad) both are Waterbenders
Obviously the Unknown Father for Lin is clear to see as are Bolin and Mako’s parents

Now on to the probending Rules we have seen most of these from Episode 2 and Bryan’s video http://korranation.tumblr.com/tagged/bryan

But here we have the full rules

So we have a few interesting points in these full rules.

Injured Players cannot be replaced
Not allowed to hit the roof !
Water and Fire blasts can only be 1 second in duration
Earthbenders cannot break the disks up, for safety and must remain solid, but they can bounce them off the ropes
There are Yellow and Red fans like yellow and red cards in football
If neither team makes or loses any ground then the round is decided with a face off
The referee tosses a coin and the winning team chooses which element to have a one on one match with (Earth vs earth, fire vs fire or Water Vs Water)
The Center circle of the ring raises into the air and the two benders fight with elements and are allowed to grapple, but no strikes. The aim to knock the opponent off the circle.

All of these images come from the press pack sent out to popular sites.

Korra Replaces Mulan