The mitochondia is plural. Singular form is mitochondrion. The guys at Crash Course Biology probably have a video about it. They weren't originally part of the cell, contain a little bit of their own dna, and a re pretty well explained on Crash Course Biology so go watch some Crash Course Biology on youtube. Go on. Right now.
Hey, there are many complex steps to cellular respiration. Glycolysis creates pyruvate which in terms allows for ATP and NADPH production. I suggest you use Bozeman Biology for an in depth look into it. Reading can you somewhere but models really help understand cellular respiration. edit: sorry, glyxolosis happens in the cytoplasm but is the first step in CR. sorry