Can anyone help me with a few questions on this game?

[kindajustin]

This game makes absolutely no sense to me. I can't make heads or tails of the guide here on PSNP and I'm honestly getting tired of replaying levels over and over again. I've spent the last 90 or so minutes dicking around back and forth through what I believe is the Turtle & Eel section of the Water chapter. Where are the eels? I remember them from my first playthrough. I've played this game far too much at this point, I just wanna get to the shit I need to do and wrap it up ASAP.

 

Also can you unlock Mementos on any level? When I've finally got the miscellaneous crap done I'll do the collectibles but might do levels out of order. Was just wondering if I would be okay in doing that. Any help is greatly appreciated, seriously.