You also have to bear in mind with these books that they'll list Cm7, Dm7, F#m7 etc as different chords rather than as different positions of the same shape - there are 5 easy and popular ways to play a minor 7th chord plus any number of random inventions - as Benoit says, eventually a guitarist will hopefully understand the structure of the chords, and find a way to play all the notes that works.

Learning these in 2 positions (rooted on the 5th & 6th string respectively) should get you through most situations:

Major
Minor
diminished

I've listed these because they would cover you playing any diatonic progression of chords in a straight major/minor key... and learning 2 positions to minimise the jumps across the neck. For major/minor, you do only need to play 3 strings, but the sound is pretty sparse... depends if you like that or not.

Your book probably shows minor 9th chords with flattened sevenths for example, where showing you a minor 9th chord and which note in it is the 7th would be less information to deal with, and easier to understand. You're on the right track learning the ones you like - I can play a minor 6th chord, but I've yet to find a good use for one... :D

They might not show 5th 'power' chords because it's just a root note and a fifth...