i think that one would be a good one for you. easy peasy. as far as what to do with the colors. my inclination is always to cut and weave the ends in and then start the color again when you are suppose to. especially since the colors are so far apart from each other. if it was 4 rows of blue, 4 rows of green, 4 rows of blue again i would say just carry it up the side but you don't want to try to carry the black al the way to the end, too messy in my opinion. So i would cut off the yarn leaving enough of a tail to weave in and then just pick up the new color at the beginning of the row. YOU CAN DO IT!!!
and doing it on circs means you don't have to worry about dropping a needle because it will always be attached to the work and when the work starts to get big, you will have the weight of it in the middle there for you instead of on the one needle!
and now that i have typed all that, let's see who beat me who isn't quite as wordy as me!