I really wish I could like iPhoto, but I don't know what in the world it is doing, and by locking me out of the Finder access to the iPhoto folder and doing things like duplicating photos without my asking, I've lost trust in this piece of software.
First thing is: It's a Photo manager. That's the basic key thing you need to grasp. Your photo is not the same thing as the file that contans it. That's why Finder access is not relevant. Import the Photo, manipulate the photo - losslessly - and then if you want to use the Photo in a document, upload it, whatever, put it into a new file designed for that purpose.
The illustration I use is as follows: In my iTunes Library I have a file called 'Let_it_Be_The_Beatles.mp3'. So what is that, exactly? It's not the song. The Beatles never wrote an mp3. They wrote a tune and lyrics. They recorded it and a copy of that recording is stored in the mp3 file. So the file is just a container for the recording. That container is designed in a specific way attuned to the characteristics and requirements of the data. Hence, mp3.
Similarly, that Jpeg is not your photo, it's a container designed to hold that kind of data. iPhoto is all about the data and not about the container. So, regardless of where you choose to store the file, iPhoto will manage the photo, edit the photo, add metadata to the Photo but never touch the file. If you choose to export - unless you specifically choose to export the original - iPhoto will export the Photo into a new container - a new file containing the photo.
So as long as you're hanging on to the idea that Photo=Jpeg iPhoto is never going to work for you.
If you're willing to let go of that - as you do with Addresses, as you do in iMovie, Lightroom, Final Cut, APerture - then you can begin to make sense of iPhoto too.
Regards
TD