Is it permissible for the Imam to call the Adhan and the Iqamah for prayer, and then lead the people in prayer?

There is no objection to combining the call to prayer (adhan) and the imamate for one who is qualified for both. The Shafi'is deemed this desirable, and Imam An-Nawawi affirmed its correctness, despite some scholars disliking it. However, there is no sound evidence to support this disliking.