What is the meaning of "Kumah Hashem li'Mnuchasecha"?
Radak: Rise from the other places, which were Mishkan, to this place, which is Your permanent place of rest.
Malbim: Those who carried the Aron reached the place of the Mikdash. He says to Hashem, rise to Your rest - there He will dwell in a fixed way, and conduct of Hashgachah will be fixed. This is called Menuchah. It says similarly (Divrei ha'Yamim II, 6:41) "Kumah Hashem Elokim l'Nuchecha."
Why did he say "Atah v'Aron Uzecha"?
Radak: "Atah" is the cloud of glory seen at Chanukas Beis ha'Mikdash after they entered the Aron to the Kodesh ha'Kodoshim - "va'Yhi b'Tzeis ha'Kohanim Min ha'Kodesh vehe'Anan Malei Es Beis Hashem" (Melachim I, 8:10].
Malbim: They will enter the Aron to the Kodesh ha'Kodoshim.
'Rashi' (Divrei ha'Yamim II, 6:41): Also the Aron should not move about from now and onwards.
Why is it called "Aron Uzecha"?
'Rashi' (Divrei ha'Yamim II, 6:41): It is due to its wonders and mighty acts against the Pelishtim. It says (Divrei ha'Yamim I, 16:11) "Dirshu Hashem v'Uzo". Chazal expounded (Avodah Zarah 24b) that the cows that returned the Aron sang "Hoshi'ah Lo Yemino u'Zro'a Kadsho" (98:1).
