You might want to go easy on the density for your first unit. Even 75% would be a ton of hair. I would probably lean toward 70% and add more on your next order if that isn't enough hair for you.

Will you have to use styling products to achieve a style like that? That might depend on the condition of the unit. With hairpieces there is a "sweet spot" where the hair has broken in to the point that the hair "flows" well where it will look better and hold a style easily. Before and after that time I would highly recommend using a little styling product to help achieve the look you want. A little pomade or a light wax will help to hold the hair in place and give it a healthy look without making the hair crunchy.