For scanning I use an old cheap Printer HP1350 (http://www.amazon.de/Hewlett-Packard-HP-PSC-1350-Multifunktionsger%C3%A4t/dp/B0000DJQ50).
I am a linux guy, so for scanning, I use Simple Scan https://launchpad.net/simple-scan.
Sketches from a 3×5 index card result in color jpegs 20 to 30KB in size (which is almost nothing).
For image manipulation I use MTPaint (http://mtpaint.sourceforge.net/) which is available on Windows as well. It’s way easier for starters than the heavy-weights Photoshop or Gimp. So if you want to get into digital image manipulation, it is a simple starter. They have great documentation as well: http://mtpaint.sourceforge.net/handbook/en_GB/chap_00.html