If you're using a sprite for the background then yes, you do need to add any text on the screen after callding
The bug that you're seeing with the crab not moving is an interesting one - it's not moving because you are recreating the crab at 200, 200 every time the draw loop is run. So each run of the draw loop, you create a new field sprite and a new crab sprite at 200, 200. Even after you update the crab's position to 201, 200, you'll never see it again because the next iteration of the draw loop with create a new one on top.
You want to create sprites before the draw loop so that they only get created once, and then you can modify the sprite properties - just take lines 2-7 and move them above the draw loop.