I don't see how Sammy is portrayed as a sexist pig in this story by John Updike. Rather than a pig, I would describe him as an immature and young boy who is trapped in his fantasies and fairy tales that he fails to see the society in a critical and objective way. His mom still lays out his clothes for him which is an evidence of his immaturity. Otherwise, I don't necessary perceive Sammy's character as being pig-like.
I agre with #3. I don't believe Sammy is portrayed as a pig in this excellent story. He is an adolescent with the same hormones running around his body that we all have experienced. I don't think therefore that we can call him a "sexist pig" in the sense that you seem to refer to. In addition, Queenie and her crew definitely want the attention that they receive. There is no sense in which Sammy "sees the light" in terms of becoming less sexist. He "sees the light" in terms of experiencing an epiphany that causes him to reject the values and norms of his society.
Let's get a dose of reality here. Sammy is reacting sexually, not an uncommon way for teenage boys and men to respond when seeing scantily clad women. Moreover, Queenie and her clan court the attention they receive. Sexual response is not bad, nor is the desire to attract a mate. To pretend otherwise is being dishonest.
I don't understand what is meant by "seeing the light." If you mean that he recognizes his magnanimous gesture has gone unaknowledged, perhaps so, but I see no evidence that Sammy would curtail his desire for beautiful women.
I don't really see Sammy as a pig, however I could see how someone may portray him as a pig. Although he didn't say anything remotely sexist outloud we know what he is thinking. When he says things like "plump one in plaid, that I liked better from the back – a really sweet can", "I uncrease the bill, tenderly as you may imagine, it just having come from between the two smoothest scoops of vanilla I had ever known were there", and "You never know for sure how girl's minds work. (Do you really think it's a mind these or just a little buzz like a bee in a glass jar?)". Sammy is just a teenager, and of course teenagers undergo many changes... all at once. One thing they face are "raging hormones" and their sex drive is dramastically increased. So I don't see Sammy as a "pig" just a normal teenager.