Can I delete photos from iPhoto and delete originals that aren't in the iPhoto folder?
iPhoto has an internal file storage system where it saves all the photos for the events, albums etc.

You notice this, when you select an event and click "Show in folder". Then you see the whole folder with all the pictures in it.

You should treat events or albums as your folders. You can give them custom names and everything.

What I have done is:


Import all photos to iPhoto
Delete original files
Just work with iPhoto (when I want to see the photos in a folder structure, I can choose "Show in folder".


Note: I have heard that you can have an external file storage for your photos with Apperture. This is iPhoto with more functionality for 200 USD, in case you do a lot of work with iPhoto this might be interesting.