Theres lots of good info on growing in coco
As for which to buy,,,I recommend a mixture of 50-70% chips(chunks, croutons) and 30-50% coir. I like to mix in perlite and or Napa Auto Oil-dri.
I would suggest looking into the hempy method as well, for ease of growing with great results.
http://www.ladyslipper.com/coco3.htm
I don't know if I'm allowed to link to other MJ grow sites....so I won't paste them here.