1) It's extremely biased and pretty sensationalized.
2) It lists no sources for pretty much anything.
3) While it does mention he knew her age - it doesn't say when that quote was from. It might have been after the trial or during it. It's not clear at all that he knew before hand.
4) The Kinski thing - yeah, lots of young actresses looking to sleep their way to the top. Those who are underage usually don't mention it. Duh. It's not much of a pattern although it does show he tends to like younger pretty women. Most guys do.
5) This is the quote that left me laughing:

Detective Philip Vannatter, a tenyear veteran, who 17 years later would go on to be lead investigator in the O.J. Simpson case, asked if Polanski had the slightest idea why he was being arrested. "I honestly don't know," the director replied.

Phil Vannatter - head of the most screwed up police investigation in the public eye that I've ever heard of including tampering with evidence, trying to get witnesses to lie, the entire nine yards. I think that says buckets about how fair the 'investigation' likely was right there.

Sorry Paul, I don't find that one much use at all.