Erdoğan is a Ottoman and not an Islamic leader. He is using Islam to reach his goals but he is not married to it. He'll move away from Islam as soon as it no longer serves his purposes.
But will the country. Like other populists found out, once you unleash the beast you have a job on taming it again
Islam is flexible. He'll bullshit his way out of it. Seen it first hand. Also most of his target countries for influence are already Muslim Sunni. So that should work out.
Not at all. Ottoman Sultans led a multicultural empire. There is now not a single neighbour of turkey that has good relations with them. Erdogan is an opportunist populist, not a great leader, sadly for turks
What is an "Ottoman leader"?
Essentially a Turk first and then a Muslim. Ottoman because it allows him to project hegemony because the Ottomans were the last Islamic "Caliphs".
Basically he still believes in the Ottoman empire and that his country should turn into a super-power that controls the Mediterranean. Many Turks share this idea, too.
Even a fictional character, Paul Atriades, knows that religious zeal is a beast that cannot be contained. I am more inclined to believe that as a skilled politician erdogan should be well versed in history and politics to see that danger. And I believe that he indeed is a believer of Islamic religion.