A tiny amount of dust inside a lens usually does not affect image quality, especially if it’s near the front of the lens. Zoom lenses can draw in dust over time, and small internal specks are often harmless in actual photos.

That said, on a brand-new lens, visible internal dust is not ideal. If it bothers you, returning or exchanging it is reasonable.

The dots in the viewfinder are likely separate from the lens dust. If they don’t show up in photos, they’re probably on the mirror, focusing screen, or in the viewfinder optics rather than on the sensor. Those marks are usually only a viewing annoyance. A gentle air blower may help, but don’t touch internal surfaces.

If you suspect dust on the sensor of a truly new camera, that could be a sign it was handled before sale, and an exchange would also be reasonable.

In short: small dust specks are usually harmless, but for a new purchase, exchanging it is fair if you expect it to arrive spotless.