Wheels, for the first one, creat a plane that is tangent to the face of the cylinder. Then make a cylinder which is can be used to create a hole in the first cylinder. Than make a circular patter. I hope this might help. I am not sure about the second one. Havent used auto cad for 3D-2D conversion. There might be some option to activate hidden lines while creating 2 D from 3 D. Play with F1, u might get success.