Lead sheet gives you song form, chord changes, and melody (head). What more is there to say? Approach it however you want. Apply some concept to make it sound like what you want it to sound like. If you want to play jazz, you must listen to jazz until you are quite familiar with what it sounds like.
As far as the significance of the chords you asked about, this tune "All Blues" is a really straightforward 12 bar blues in 6/8 time. You need to know about blues form and feel to play jazz, so get cracking. First listen to the jazz tunes from the lead sheets and you'll figure out what to do. Just realize that nobody knows or has ever known everything about jazz. As the tired cliche says, "it's a journey, not a destination".