Where to start here?
One wonders why these pictures were doing in the trash to start with but we'll just have to accept the fact that they were.
Drag the pictures out of the trash and put them in a file on the Desktop.
What makes you think that you have lost iPhoto and System Preferences?
Can't see them in the Dock anymore?
If so, that's not a problem, those are only alias' anyway. Open your hard drive and go to Applications.
Inside there you will probably find iPhoto. Click it and drag it back into the Dock.
Repeat with the System Preferences app which is also in the Applications folder.
Now launch iPhoto and see if you have any pictures in it.
Let us know what happens