iPhoto tries, for better or worse, to remove the need to know where the photos are in the filesystem (e.g., the finder). It's got its own way of categorizing photos, generally in this type of folder structure:
year of photo -> month of photo -> day of photo.
All of these are within the iPhoto library folder in your Pictures folder. I say "generally" because there are times the photos aren't tagged with exif info properly. If the date/time on your camera are off, it's going to be inaccurate. I'm not sure how it works with importing. I suppose it depends on what kind of exif info stayed with the photos when you initially imported them.
While I know how to find photos pretty easily (and now you do too), it can get complicated when you make changes. iPhoto makes a duplicate and applies changes to that duplicate, this way the original photo remains untouched. But all you'll *see* in your iPhoto library is the changed photo. And chances are, the touched up photo is the one you want to email.
What I do is just export the photos I want to find to the desktop, do what I want with it and then delete it from the desktop. If I'm exporting a bunch, I'll create a folder on the desktop for temp storage and then go from there.
The thing you need to remember is that this is probably the best way to deal with photos (and these types of data generally). I don't know about you, but I've got thousands of photos. And they're all easily findable within iPhoto. Why deal with a filesystem that's not ideally suited to this type of data when you've a nice clear window to see exactly what you want? Same goes for letting iTunes organize your music. It's just *better* that way. Not because you can't do it yourself, but because with proper metadata, the best way to do it is simple and ideally suited for a catalog program like iPhoto or iTunes.
Let go of your need to control your files and you'll be a happy camper.
Welcome to the Mac.
edit: I just realized that I didn't really respond to your second post. I've gotta ask "why?" do you want to do the file management? Seriously. Think about it for a minute. You may have good reasons but most people just think that they *should* without having a real reason. Just my 2¢.
edit2: iPhoto is actually an "Apple Product" so it should be in that forum.
