I love Lupin and Tonks! I swear, at the end of the sixth book when Tonks started yelling at Lupin and telling him that she didn't care that he was a werewolf I cried it was so awesome! I also love the backstory on Pottermore!
Harry would have told Teddy from the start because he himself had been lied to about his parents death. And of course they are all famous in the post war wizarding society, theres no way Teddy doesn't know.