Should I organize RAW files manually?

Your choice - but it will not save disk space

When you import an image into iPhoto by default and extremely strongly recommended makes a bit for bit copy of the original image and a JPEG priview of the image plus a small thumbnail - if you convert the RAW prior to importing then you increase the disk requirements because you have the original RAW image outside of iPhoto and the converted (probably) JPEG original in iPhoto plus the preview and thumbnail

LN

No. It will save exactly no disk space.

When you import a Raw iPhoto copies it to the Library - that's the original - and makes a jpeg preview. NO matter what app you use you will always have an original and some sort of processed version if you're using a non-destructive workflow. You might, if you don't some any kind of photo manager, save on a 250kb thumbnail. That's pretty insignificant.

If you go for a destructive workflow then it's hard to see an advantage in shooting raw, but it will use less space.

If space is an issue don't try "free up space", get more. Hard Drives are inexpensive - quite massive ones, up to a terrabyte and more now. Sooner or later - whichever system you choose - you're going to use up the space unless you stop taking photographs.

You can run an iPhoto Library from an external. And an iTunes one too.

Make sure the drive is formatted Mac OS Extended (Journaled)

1. Quit iPhoto

2. Copy the iPhoto Library from your Pictures Folder to the External Disk.

3. Hold down the option (or alt) key while launching iPhoto. From the resulting menu select 'Choose Library' and navigate to the new location. From that point on this will be the default location of your library.

4. Test the library and when you're sure all is well, trash the one on your internal HD to free up space.

Regards

TD