Dihedral & Wing Vertical Location.

Wing location on the fuselage can affect the roll coupling of an airplane. Picture a plane with a low wing. Let's say you put in right rudder. Now the air flow is hitting the left side of the plane. The air flow tends to split at the center of the fuselage with part flowing over the top and part over the bottom. On a low wing plane, the flow going over the top of the fuselage goes over unrestricted and joins back up with the airflow. But, the part flowing under the fuselage hits the top of the left wing, pushing it down, causing a left roll, opposite to the rudder.

Visualize a wing with dihedral in a right yaw. With the wing cocked to one side, the air flow is now hitting the bottom of the left wing and the top of the right wing, causing a right roll. Conversely, anhedral causes roll opposite to the rudder.

This is the reason that most low wing planes need dihedral. The dihedral causing roll with the rudder should cancel the low wing location causing roll opposite to the rudder.

Conversely, high wing planes steer in the direction of the rudder. This is why Sticks with flat wings, like the Ultra Stick, will still roll in the direction of the rudder. High wing planes need anhedral to cancel the wing location and be neutral with regard to roll coupling with rudder.

Wing sweep does the same thing. Visualize a plane with swept back wings with right rudder. The right wing is now more in line with the air flow and produces slightly less lift. The left wing with right yaw is now more square to the airflow and will produce slightly more lift causing a right roll. Sweep back produces roll in the same direction as rudder. With a swept wing, you need less, or no, dihedral in a low wing plane. Sweep forward produces roll opposite to the rudder.

In summary,
High wing, sweept back and dihedral produce roll with the rudder.
Low wing, sweep forward & anhedral cause roll opposite to the rudder.

A designer can make estimates as to what he needs, but it is really a "cut & try" type thing to get all the roll coupling cancelled out.

With regard to your nose dropping, you may have some pitch coupling or you may be unconsciously corecting for the roll coupling, causing a slight loss os speed and the nose to drop.

Pitch coupling is another mess that is hard to correct. Computer radios and mixing will work, as will canopy location, side area, gear type, tuned pipe location and CG.