Live rock is not a substrate. Live sand, or dry aragonite sand would be considered substrate. For a 65G tank you definitely want a protein skimmer, and you most likely would not be able to get by without one. For a tank that large, proper filtration is a must, and while a sump is NOT required, it is in your best interest to obtain one. A sump will allow you to have more water volume throughout your system, and will contribute a big part to having better water quality.
The live rock will count for biological filtration, which will play a big part in filtering your water, but 65G is a lot of water, so live rock alone won't cut it. Also, for a tank this size, you won't be able to skimp on a protein skimmer. You will want the best one that your budget can afford. One type of skimmer i would stay away from is the Seaclone. Types of skimmers that are great are Venturi, Reef Octopus, and a couple others i forget the names of. A great place to look for skimmers is at Aquarium Supplies - Aquarium Supplies for your Tropical Fish, Saltwater Fish, Reef Aquarium, Marine Fish, Saltwater Aquarium
Their prices are excellent and shipping is only 4.95. However, they may charge 6 or 7 $ extra if it's a heavy item.
For more on skimming, i would advise strongly on reading this article from our very own AA: