you tell if the joint orientation is good by seeing where the red line points.
if it points down the joint then it's good
it means that it will rotate as you expect
obviously if the joint is a leaf node (has no children (has no joints coming off it)) then the joint orientation doesn't matter because it doesn't affect the position of the other joints
i've attached a picture of a selected joint chain so you can see which red line i'm talking about


as for moving by using insert... have you tried moving it normally?
if you move a joint normally you move all it's children as well (all the joints attached to it)
if you move it by hitting insert you just move the joint itself. it's the same as hitting insert on an object to move the pivot point, you're doing the same thing, moving the pivot point of the heirarchy of joints
so basically you do it when you want to move the joint itself and not the children underneath it