To have a easier time getting the achievements in this game: Pause the game, go to Game Settings, select 5 lives and activate Round Select, you will get the achievements with ease this way
The Oranges appear below the Ghost House after eating a certain amount of Pac-Dots, when the Orange shows up, stop everything you're doing and eat it, or else, it will disappear and you'll have to either reset the game or try again on Round 4. You'll get the achievement once you eat it.