What I am learning and/or deducing is that pictures whether captured in RAW or JPG format are captured never to be released from the library they are imported to.
File -> Export... ?
It seems that when I delete them using the trash function they do not seem to be physically be removed from the library they only seem to be removed from an index/database.
Not so. If you use a Managed Library the files are sent to the System Trash, and removed from the HD when that's emptied. If you use a Referenced Library then you have to manually remove them from your own filing system after removing them from iPhoto.
IPhoto reflects that the the event is gone, but IPhoto manager still see's them in the library even though they were deleted previously.
Library Manager doesn't read the actual library. It read the xml file that used for Sharing with other apps. This should be updated, of course, when you delete the event from iPhoto and empty the trash. If that's not being read by Library Manager you need to contact the makers of that app for assistance.
SInce I have only found one library file associated with a specific IPhoto library, I assumed that the database and the library were contained in the same file.
That's not a file. It's a Package. It looks like a fie but it's really a folder. You can see inside simply by right-clicking on it and going 'Show Package Contents'. Standard Warning: Don't change anything in the iPhoto Library Folder via the Finder or any other application. iPhoto depends on the structure as well as the contents of this folder. Moving things, renaming things, deleting them or otherwise making changes will prevent iPhoto from working and could even cause you to damage or lose your photos.
The Library is: all the original photos, plus the database files, caches and metadata files.
If I take 10,000 pictures and only want to keep 70% or less of them, I sure don't want to waste limited disk storage retaining photo's I have trashed/deleted.
As explained above, that doesn't arise.
On the same hand If all pictures are captured at 15 megapixels or greater I may only want to keep a handful of high resolution pictures while the rest would be fine to keep at 8 megapixels.
iPhoto is all about lossless processing. There is no way to scale a 15 mp image to an 8 mp one in iPhoto, as that's a lossy process. iPhoto is not that app for you if you don't want lossless processing.
Given than iPhoto can manage 1,000,000 in any library, that it can have multiple libraries, that it can store libraries on external disks (as long as properly formatted) I don't believe that you have any worries about growing your library. We've seen reports on here from people with in excess of 300k images in an iPhoto Library. One user on the Aperture forum reports using it with 400k images.
Not sure I know of a primer on the Library, so here goes:
The apps use masses of virtualisation. Files are never edited. If you import an image to either it is stored and indexed. If you edit the image then your decisions are recorded in the database. If you view the image your decisions are overlaid on a view of the original image. To get edited photos out you need to export or use the sharing mechanism based around media browsers.
The library has no user parts at all. If you opt to use iPhoto or Aperture then you do everything either with or via these apps - and everything you need to do can be done via them. You simply never access the images via the file browser.
Regards
TD