2001 GS-500E Questions - First Post - New to the Board

[Denny Lee]

Ya'll,

   I have just - or will on Monday - pick up a very clean, stock 2001 GS-500E with 15,000 miles on it. I have rebuilt / or reclaimed many bikes over the years and just need the collective wisdom of the board to steer me in the right direction.
   (Numbers / Recommendations for:)
  Spark Plugs -
  Oil capacity -             and weight -  10/30   10/40 ?
  Front Sprocket -                      Rear Sprocket -            (thinking of going 17 teeth on front / 39 Rear - thoughts?) 
  Fork Oil weight and capacity -

  Also,  are there any things I should be aware of that give problems?  Rectifier? Stator? Starter Relay? General electrical gremlins I should address or look for?

   I'm trying to stay away from deviating from stock, but would a freer flowing canister exhaust with no other mods require a rejetting?

TIA