iPhoto needs to have the Library sitting on disk formatted Mac OS Extended (Journaled). Users with the Library sitting on disks otherwise formatted regularly report issues including, but not limited to, importing, saving edits and sharing the photos.
So, unless you can find an appropriately formatted Server that's not going to work.
iPhoto has no cross platform ability whatever. Running a Windows app cross the library might well damage it, and much of the metadata - Faces, Places, Keywords, Album, Smart Albums and so on, simply will not be available to it.
If space is an issue you can easily move the Library to a disk appropriately formatted.
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
Regards
TD