As for printing four pictures on one sheet of paper, there is Al's method, or:
* Open a new document of the size of your sheet of paper
* Open your picture in PS
* With the pic active, press (on mac Ctrl means CMD)
-Ctrl+A to select all
-Ctrl+C to copy it to the clipboard
* Activate the sheet size doc, and paste (Ctrl+V) four times your picture from the clipboard. All four will be on different layers. Activate each one, and drag them as you wish to make your lay out (you can use snap here!)
* When all is well and you feel happy about the lay out, then activate the bottom (sheet) layer, hold down controlwhilst clicking on its icon in the layers palette to select all, then go to Image>Crop. This way you get rid of the surplus that is outside your canvas and adds to your filesize.
You can flatten if you wish to do so, and print with preview.
Not the most elegant method, but it works.
Al's is more up to date.
