As implied, there are other considerations around which cut you use and how you prep it, but regarding the original question, aim for an internal temp of 180 degrees which should take about 40 minutes per lb at 300 degrees oven temp.
Another trick is after cooking the roast then letting it rest for at least half an hour, crank up the oven to 475 degrees then put the roast back in for about 15 mins. This gets the outside nice and crispy. I would probably do that on a clean baking sheet instead of back in the DO.
From a terminology POV, roasting and baking are essentially the same thing, indirect heat in the oven, but the technical difference is this: cooking something that already has a solid structure, like meat and vegetables, is roasting. With baking, the solid structure is created during the cooking process, such as a ball of dough turning into a cookie.