Exact match kw anchor in backlinks is ok, in a given percentage of total. Lower for long tail, and higher if the kw is brand name. Mix exact match with branded anchor and with some naked url. Close match can be treated as exact match. Now, internal linking. First of all, if the site is well structured, Google is very likely to understand what header, footer and sidebars are, so we discuss links from content. I am sure you have a lot more freedom to use your choice of anchors, but still, doesn't hurts to mix it a bit. For example, branded anchor inside, not so much, naked url either, but exact match mixed with close match and other variations, might do good