1: Texture is very important in sketches because it helps to define what the subject of the sketch is and adds detail as well as some depth. Using the texture can also help eliminate the empty and open space of a sketch. Texture makes a sketch distinct and quite life-like.
2: Refrences are very important in art and help with sketching. You can pick out your favorite things in each picture and combine them to make your very own. Refrences are also helpful in creating depth. Seeing several different veiws can assist in drawing the subject so you can include all the different angles to make the sketch 3d.
3: When looking at my three different sketches I can tell which will be the best print because of texture. Like in question/answer one, you need to be able to see depth in the print as well as using up all the empty space. My favorite sketch includes lots of texture on the animal but less texture in the background so that the subject of the piece, the animal, stands out and makes the veiwpoint of the picture.