Congratulations on you're new bow. You handle all the strings the same, just twist to shorten. Anywhere between the lines is good but if you are want to be like some people here wait until the string stops stretching and then experiment with different positions between the lines. Some where between the two lines will yeild the most accuracy. I usually try to get it real close to the forward line to give me the lowest brace height. Donno if there is a difference in speed if you give it the min brace height but I can only imagine you do get a tiny bit of speed from a low brace height.
They are all awsome bows!