The first quote is proverbial, and Newton certainly said it, but the phrase dates from the 12th century (http://en.wikipedia.org/wiki/Standing_on_the_shoulders_of_gi...) and is not part of Enlightenment tradition. Quite the opposite, in fact: it comes from the medieval tradition of abasing yourself before the ancients. So no, it doesn't resemble the disputed quote at all.

The second is not familiar to me, but it is 17th century language and does sound like something Newton would say. But it's irrelevant here. He's talking about nature, not himself.

The third is much closer to the disputed quote. But I don't believe Newton said this either. You know who said things like that? Horatio Alger. So let's see a textual source in Newton's works before accepting it as evidence.

Here's a helpful trick. When you Google a quote and the first page consists entirely of junk like this:

http://www.google.com/#sclient=psy-ab&hl=en&source=h...

... that's a sign that the quote is bogus.