Should we say the Athan and then the Iqama for prayer, or is the Athan from the device sufficient?

The Adhan (call to prayer) is a communal obligation (fard kifaya). If there is no one in the city to perform it, it becomes obligatory upon its inhabitants to establish it. The Adhan from a timer device is not sufficient in place of a direct, live Adhan. If there is a mosque far from you where the Adhan is called, then the Adhan is not obligatory upon you, but it is commendable. As for the Iqamah (call to commence prayer), it is commendable and not obligatory.