you need to complete all the chapter and the chapter in which harry obtained the philosophers stone in the same chapter you also can. i think so at least. if my answer is wrong. i am sorry then.
alchemists only believed that their was a philosophers' stone
In Harry's pocket. You click the mirror and he winks and pulls the stone out.
Doodle God 2 Philosophers stone + sand (sand=stone+water) (philosophers stone=demi god+quick silver)
Yes, you can find many things. For a guide per chapter see the Pottermore Wiki.
Philosophy+stone
Philosophers stone plus metal equals gold. Wizard plus energy equals philosophers stone.
demigod+quicksilver=philosophers stone
Alchemists were the ones looking for the philosopher's stone.
Elixir of life.
he was 10
You can make gold. Metal+ philosopher's stone
Demigod + Quick Silver = philosophers stone