Yes, plants do respiration, and yes much of it occurs in mitochondria. Plants are not different from animals on this score. Much of what you already know about applies directly.
Respiration is both a degradative as well as a synthetic pathway.
Intermediates can be taken from the path for a variety of purposes in cell biochemistry. Transparency from page 113 of text. Electron Transport and Oxidative Phosphorylation Transparency from page 119 of text. Transparency from page 123 of text. To learn more from this, check out the readings comments for Chapter 6 .