He simply wasn't interested in finding the One Piece, and for him, his only treasure was his family. Just as Roger found his treasure, Whitebeard found his as well.

Did Whitebeard acknowledge Luffy?

Following Ace's death, their top priority was to save Luffy from Admiral Akainu, as ordered by their captain, Whitebeard. The Whitebeard Pirates came to respect Luffy highly.

Is Edward Newgate a giant?

Whitebeard was an abnormally large man, with a height of 666 cm (21'10"). Unlike other large-sized humans, however, he was well-proportioned. He had a long face, ploughed because of the advanced age with many wrinkles around his eyes, and many scars running along his chest, and was very muscular.