I draw the diagram a little differently, as if it were a Lambert chart, so in the northern hemisphere draw the meridians converging at the top. GCs are straight lines a to b and rhumb lines are concave to the pole. From this diagram you can see exactly what should be happening to your GC track (increasing or decreasing measure relative to the local meridian).
1) Your GC changes by Earth Convergence between A and B, not by conversion angle. Remember that CA = EC/2. So to go from A to B in the northern hemisphere you start at A on 040T and arrive at B on 048T since going east in NH you add the angle change. 042T would be your track midway between A & B. The reciprocal to go back B to A is therefore 228T.
2)CA is EC/2 ; EC= chlong sine Lat. Remember that for this question in the middle the GC track is the same as the rhumb line track of 090. CA converts between GC & RL track at the middle, not between GC tracks at your start point and destination. So in the middle of the trip GC track = 090T and to go back the the start add the CA (42 degs) since you are going back to the west in the southern hemisphere. Between A and B the GC track changes by earth convergence of 84 degrees, so the track at B is 090-42 = 048T. Subtract going east in Southern Hemisphere.
Good Luck!