The first step of a triple step should be a normal sized step. The point of triple stepping is the center travels beyond the balance point hence the second two steps. If the first step is overly large your center never reaches the point where a transition is necessary and it kills the flow and rhythm of the step.
The rock-step has no set placement. PErsonally I would question any teacher that ever says you must step in a certain place for a certain step. A leader moves his body as necessary to properly lead the follower. If she is off to one side, does not travel far enough or travels to far your body is going to need to change its distance and orientation to compensate... this means the placement of your foot must change. A follower's body placement is dictated by the leaders movement, her feet need to stay "underneath" he body to keep her from slipping, sliding, or stumbling. IF a follower attempts to follow imaginary (And not so imaginary) footsteps on the floor she is going to quickly find herself commiting the one cardinal sin in partner dance... not dancing with her partner.
Sometimes you will rock step in a straight line, other times it will be rotational... it should rarely "hook". Hooking on the part of the leader provides no direction for the follow, it instead provides rotation and usually grounds her immediately after. Hooking on the part of the follower is just like any other step... it should be a natural response to the leader's movement of your body unless it is part of an improvisation/syncopation in which case you need to ensure that it in no way inteferes with his leading you.