It's not so much the motor thats a huge deal but when you have such a wide angle and a telephoto end that long the lens usually sacrifices image sharpness to get you that range.

There is no difference in image quality in memory cards but there is different classes like four, six, and ten. The higher the class the faster your pictures will transfer which is useful if you continuously shoot high frames a second. Also I always use Sandisk and never had a problem losing files over time which can happen with some cards.

Memory cards are not meant for permanent storage and eventually they do lose some information over time. Saying that I still keep my original pictures on them just in case. I missed a few good pics when i went to check a few of my cards i never downloaded. Also the price of memory cards have come down so far in price.