He (AS) according to our beliefs will be a leader like the early Caliphs of Islam. Yes, he will revive the true spirit of Islam.
His first mission was to unify the lost sheep of Israel. They were lost in the spiritual sense and he guided them. That is the principle lessons which are still somewhat preserved in the current Christian scriptures.
His second mission was for a sheep not of that fold. But of the coming era. An era near the end of time. Just as you believe, however, albeit in a different body. Isa (AS) was the manifestation of the Torah and the Injeel and shall be a follower of Qur’an and Sunnah on his arrival. This is our belief and I agree this is where we part ways with the Ahmadiyyah.