search for Jason Schleifer. he is a god when it comes to rigging. I somehow remember that I learned a lot from his work. since it is quite a while and I never got a chance to work in the rigging and animation section I forgot the most of it. but JS´s site is a hot place to look. also Paul Thuriot from Tippet studios made some awesome scripts for rigging. I read a lot about LRA-issues in his works as well. why I refer to those people? coz I had a hard time understanding LRA and all this stuff too. did spent a lot of time working out from basics to advanced stuff.
basically lefthanded I think means the X-axis pointing down the joint. if you then rotate the z-axis of the joint in a positive direction it should bend the joint in a natural angle. like the knee back not forth. so you would have to setup the LRAs in a way every bone bends natural when you rotate it +Z.
sorry for my lack of memory of all this stuff. I am sure anybody can give you much better explanation on this. but if LRA is as confusing for you as it was for me, try and get as much ressources as possible. Jason Schleifer and Paul Thuriot would be the best place to start I think - besides vladimirjp and Jay from this forum who helped me a lot. maybe you find something in an old thread of mine to.
everything starts and ends in the right place at the right time.