I'm not familiar with Photoshop LE, so I'll let someone else who is give you pointers on that. Here are my suggestions.
I find that the Nikon scanners scan Provia extremely well. If your friend has a CD-ROM writer, have him make raw TIFF scans of 10-20 MB each. This should give you plenty of leeway if you want to crop down, or if you want to zoom in on something like a small registration number. If you have to use floppy disks, you're rather limited.
With the original image, rotate the picture if you need to to get things level, and crop the picture so that the plane is "flattered" the most. Apply any color balancing, contrast adjustment, saturation, etc. at this point.
Resize the image to 1024 pixels across, maximum 768 pixels high.
Use the Unsharp Mask to sharpen the picture as much as possible, without allowing the picture to get grainy, or that edges start getting jagged. Pay special attention to the sky and dark areas like engine intakes, as those areas seem to start going grainy first.
If some areas are starting to become grainy, but other areas could still use some sharpening, use masks to selectively sharpen these areas.
Save the file in jpg format, with no compression. the file should be in the range of 500-600 KB.
Collect all appropriate info on the aircraft, and upload.
The only thing you should feel when shooting a terrorist: Recoil.