Yes, I can see "chador ate' topo = to reach (or arrive) at the top. However, "pode chegar ate' nose = can reach (or arrive) until us" is still a bit confusing or me. Can you define ate' is this case, please? And, would the use of "atinger" be inaccurate as a substitute word?
Nope, this is a different type of pronouns, called prepositional pronouns (since they are the object of a preposition), which you should use after other verbs that call for prepositions (the first and then most emblematic/common example in the Duo course is gostar [de]).
You can read more about them here: http://www.nativlang.com/po/qg_pronouns_prepositional.html