Thank you everyone,

Sorry that some of them questions might seem dumb for you, but I'm just starting and trying to make it right ... you are right, I will not need to load all them images for background at once... and meanwhile I've also realized something, some of my animations...need not be (well I think none of them) in 16bit , probably will seem stupid but I just realized my Moon animation, only needs 4bit instead of 16bit, I did not know that 4 bit can hold any kind of four colors (for example 4 shades of yellow) ...

Thank you again!!!

Rob