The whole nine yards refers to everything that is relevant. Bob took everything he could think of on his overnight camping trip...tent, sleeping bag, compass, gps, ice chest, hand axe, emergency signal flares, the whole nine yards.
Double take is a delayed reaction to a stimulus where someone looks at something that normally would be immediately noticed, but continues on a bit before looking again at whatever is was that should have been immediately noticed. Origins in comedy/theater. Or like Mustaine and RPM said are good examples.
Les