As you say, the things he's saying on the first meeting are just the things his parents have been telling him all that time. I wonder if he's met Crabbe and Goyle before? It's tempting to see his situation when boarding the train as really rather similar to Harry's - alone, in a large group of children that he's never really had any contact with, and looking to make friends despite the handicap of his background. Then he meets Crabbe and Goyle and that altercation with Harry, Ron and Hermione happens - but if he hasn't met Crabbe and Goyle yet, all Draco is really doing in that scene is try to show off to his new friends the way his father always does, because that's how he's been taught to act. Then his early associations and those of his father determine his later course in Hogwarts, largely thanks to the system with the four houses which encourages clique formation and rivalry and strife, and in the end the evolution to budding Death Eater is a fairly natural one. The way his father buys him a spot on the Quidditch team in Chamber of Secrets is lame and pathetic in the eyes of the protagonists, but it also tells us that Draco is under significant pressure from his parents, who are interfering more with his life at Hogwarts and with his friends than he might actually like. I think he's rather lonely, despite the appearances, from the start, not just in book six. His bought or wowed friends can't be much of a support, especially not in competitive and merciless Slytherin.

One of Rowling's greatest strengths, as has been mentioned in several posts here already, is to write a children's story that has additional layers for adults without giving the children the feeling they're missing anything. I suppose it could be the benefit of hindsight that creates most of the shades of grey in these earliest novels, but for both Draco and Snape there is some grey even in this book when viewed alone.