For the PS version, there is exclusive content to be found through secrets. I believe you refer to those?
Though I have betatested those areas, I'm not sure where the secret entrances have been hidden in the PS versions, so I cannot help you with that.
As for the secret ending, you have to find some secret areas and once you do that, ring the last bell once more.
Note that I'm not exaggerating if I say that there are as much secrets as it takes you to complete the game itself.