sounds like your computer screen is having some coloring issues. try fooling around with the options until the pictures look better,

Try adjusting the White Balance - page 53 in the manual. Helped my pictures a great deal.

I am pretty sure that you can use any size SD card in this camera. What I would suggest, however, to get maxium performance is to look for a Class 10 SD card. You can tell the class of the SD card by looking for a symbol that is a C with a number in it (2,4,6,8,10). The higher the number, the better the performance of the card. Where this comes into play is with save speed and quality of the file. My 4GB Class 10 cost $30, but it is worth the money I paid for it. I have little to no wait time for images to save to the card, which helps improve battery life as well as my ability to snap photos quicker.