nicely said. I think it essential that you don't stick to a same bumlio but to listen to many different versions of the song and get the feel for it, then turn and expand it in your own way with relative but not over emphasized roots to the original desipher.
Dark star is a great great song and the jammin can go on forever, i think when attempting to play dark star with a band it will probably hold some of the basic riffs for a while then intime fold out a whole new different glob of creative personal flows and riffs which could be caputured by a recorder of some kind, and in time of playing it with acceptional musicians, using rememberence of previous jams of yourself (which originated from the original dark star), Dark Star can be taken to various depths of the universe alfoat the creativity of its listeners changing but not endangereing the original feel of the song.
Alot of grateful dead tunes are like that, giving you freedom to walk on or create new pathways to any destination. ultimately i think the jamming, if played continuosly with a group, could lead to great new songs with much creativitey.