Just retired, so planning to get more active in photography. Want to do some printing (outside labs) and photo books, so I wondered if calibration software and hardware is strongly advised. If so, I'm leaning toward Spyder4Pro because it also offers a HDTV calibration add-on package. So 4 questions:

1) Is calibration software/hardware advised?
2) If so, for those with Spyder4Pro, what's your rating?
3) How are O/S update versions, such as Apple's move from Mtn. Lion to Mavericks, handled. Is there a free update provision with the Spyder software for downloading , per the example, Mavericks compatible Spyder software? Or must you buy new Spyder software with each new O/S version that you install?
4) If anyone uses the Datacolor HDTV calibration add-on, what's been your experience?