Hello,
to #1:
1. I've added a sketch
2. use cosine rule: The resulting force divides the parallelogram of forces into 2 congruent triangles. 2 legs of the triangle are the known forces and the included angle is . Therefore the resulting force is:
3. to calculate the angle between the force of 10 kN and the resulting force use cosine rule again:
.......Plug in all values you know:
In my drawing I've measured the angle between the x-axis and the resulting force.