hey UB, great to see another GNR lover! Slash is probably one of my favorite rock guitarists. As for scales, you'll find that in a lot of GNR songs it will change from a pentatonic to a major/minor, or vice versa, thus giving the song some added power (songs that change keys off the top of my head: Sweet Child of Mine, Rocket Queen, November Rain, Civil War). He'll quite often use a pentatonic and add in extra tones to create more tension in his solo, he almost never sticks to one particular scale throughout an entire song. As far as technique, he is greatly influenced by Page and other blues-rock type players, and you can tell in his playing (he uses a lot of bends, uses the blues scale on occasion, uses lots of tradition blues licks), and also takes this to new levels by having a great energenic hard rock sound and feel. He uses a lot of hammeron pull-offs, I've never heard him really shred (fast picking runs, that is) for more then a few short little phrase.

Sweet Child of Mine is in D major (1/2 dropped tuning). The solo starts off in D harmonic minor, then changes to E pentatonic for the second part of the solo.

Any other questions feel free to ask.