Another preloader question

I apologize for posting another preloader question but I have been trying to figure this out for a while without success…

I have an photo album where I would like to preload a few (about 10) images and the veiwer can click on buttons to view each image.

  1. Is it better to preload all (10) of my images, or preload them seperately when the view clicks on the button? Why?

  2. How can I preload more than one image at once (with the loader bar moving from 0% to 100% for the total number of images, not each individual image)?