Hi,
not sure if you´re intending to do post in 5.1 for TV/streaming or theatrical, but here are some generalist resources that cover pretty much a lot. Some formats described in these docs are now being phased out or are legacy but the basics still apply to nowadays practices:
http://www2.grammy.com/pdfs/recordin...rs/5_1_rec.pdf
http://www.voesd.at/files/Multichannel_Music_Mixing.pdf
If you´re working with Protools, I find this video really helpful:
https://www.youtube.com/watch?v=tZeKaHyZ3ig
Of course that today a lot of people are moving to formats larger than 5.1, like Dolby Atmos, Auro 3D, DTX-X, that use larger speaker layouts, including the vertical pane, allow the use of audio objects along with the traditional 5.1 or 7.1 speakers and provide a better sense of immersion. Nevertheless, despite all that, if your studio clients don´t ask for it, or if the market you´re in doesn´t deliver in those formats, it´s a waste of money. Despite all those considerations, is always good to have the knowledge, so I think you should also try to get some info on those formats as well.
