Any of the first three sai brushes listed in my FAQ can acheive the different looks in these palettes. It's merely up to preference which works best for you. I also had my stabilizer at about 13 when I did this, if that helps.
Hmm well I suppose it depends on how the hair colors are layed out. If it's like different streaks it's easy to separate the colored strands, but if if it's a gradient it's important to make sure to convey the subtle color changes and mixing of hues. It's a little more complicated but totally doable.