This sentence comes from chapter XXII of Lingua latina per se illustrata: Colloquia Personarum (emphasis mine in the word I find difficult to understand):
Putāsne mē tantum atque tam pulchrum ānulum aureum octō sēstertiīs vendere.
I understand its meaning, but I have some doubts about its construction. The first one is that, because of the presence of -ne, I believe it's a question. So, shouldn't it be an interrogation mark at the end?
The second one is about the role of the conjunction atque. I think that the sentence makes sense without this atque:
Putāsne mē tantum tam pulchrum ānulum aureum octō sēstertiīs vendere?
So, what's the role of "atque" in the above cited sentence?