Another draw is this one: First of all, you should be careful with the drawing. As I said, if the drawing is correct, than nothing bad can happen. Shading is so relaxing that you could even not think of it, put some music and just shade. Also, the time you need for a draw request double time for shading. So if your draw is not precisely built from the start, you will start shading and at the end you will loose a lot of precious time and after all, the drawing will have construction problems.
And it will be a pity then.
So, the perspective here is inverse: see the top of your cube. The two lines could be either parallel or they will end by meeting at the horizon, not the other way round.
About the texture: It seems that you understood my explanations and sketches. Well done! Just be careful about the shading.
About the shading: even if you shade each small square correctly, you should be careful not to loose the volume: the sides and the top of the cube must have a color of themselves. Let’s say you have a lighting source coming from left top: then the top of the cube should be gray1 shade, the left side should be gray2 shade and the right side of the cube should be the darkest.
Waiting for next questions and drawings :)