The interesting thing about the markings is that they seem to repeat - some markings don't even get to the five counter before they're suddenly starting again. Each 'set' don't last very long too - the furthest it seems is seven, and then it starts again.

As for the other cells that can't open - the light from the torch gives a bit of illumination to generally see that most of them are pretty much the same, but unless she actually gets inside the doors themselves block out too much light to be able to really make out anything.

And about the unlocked door at the end... well, the place is certainly different from the other cells. For one, its a lot more well-furnished.