Disc laser beam power levels? (mW)

I have a few questions regarding laser power in milliwatts:

  • How many milliwats are required for reading and burning?
    • CD-R
    • CD-RW (difference between highspeed, UltraSpeed, UltraSpeedPlus?)
    • DVD-R, +R (×4,×8,×12,×16)
    • DVD-R DL.
    • DVD+R DL.
    • DVD-RW,+RW (×2,×4,×6,×8)
    • DVD-RAM (×3,×5,×12,etc.)
    • HD-DVDs, HD-DVD-RAM.
    • BD-R, BD-RE, multilayer versions.
    • Different laser power at different reading speeds too?
    • CD-ROM and DVD-ROM SL,DL reading.
  • How much do the mWatts vary in PleXtor VariRec?