Yellowstone National Park/Mt. Rushmore highways

Hoping to visit Yellowstone ... plan to stay inside the park at one of their campgrounds ... any reviews on this location?

Also - how is the highway 14 route out of Yellowstone?? Would it be better for us to head north and get back onto I-90? and go through Billings to Mt. Rushmore?

What are the hwys like around Mt Rushmore (hwys 16 and 85)??

How is traffic at the end of June? (Saw in the other thread to avoid Mt Rushmore in August - thanks for the heads-up on that).

Any advice on traveling these locations would be greatly appreciated.