Short answers, pulled from the story.
Abbas I, known as Abbas the Great, was the fifth Safavid Shah of Iran who reigned from 1588 to 1629. He is generally considered one of the most important rulers in Iranian history and the greatest ruler of the Safavid dynasty, credited with reconquering Iran's lost territories, reforming the army and administration, and transforming Isfahan into one of the most celebrated cities in the Islamic world.
Abbas the Great was born on the 27th of January 1571 in Herat, in the province of Khorasan. He was the third son of Mohammad Khodabanda and his wife Khayr al-Nisa Begum.
Abbas came to the throne on the 1st of October 1587 at the age of seventeen after the Qizilbash military chief Murshid Qoli Khan deposed his father Mohammad Khodabanda and placed Abbas on the throne in Qazvin. Abbas soon had Murshid Qoli Khan assassinated at a banquet on the 23rd of July 1589 and began ruling Iran in his own right.
The ghulam system was a military and administrative corps composed mainly of Georgians, Circassians, and Armenians who had been brought to Iran through conquest and the slave trade. Abbas expanded the corps from a few hundred soldiers during Tahmasp's era to 15,000 highly trained cavalrymen as part of a division of 40,000 Caucasian soldiers. These ghulams were loyal directly to the shah, which allowed Abbas to reduce the political and military power of the Qizilbash tribal chiefs.
Abbas won a decisive victory over the Ottomans on the 6th of November 1605 at the battle of Sufiyan near Tabriz, and followed this with a complete ambush victory in 1618 over an Ottoman force of 100,000 led by Grand Vizier Damat Halil Pasha. The Treaty of Nasuh Pasha in 1612 formally granted Persia suzerainty over most of the Caucasus, and by the end of the 1603-1618 war Abbas had regained South Caucasus, Dagestan, swaths of Western Armenia, and Mesopotamia.
Abbas moved the Safavid capital from Qazvin to Isfahan in 1598 after securing his northeastern frontier against the Uzbeks. He then transformed Isfahan into a major imperial centre with mosques including the Masjed-e Shah and Masjed-e Sheykh Lotfollah, the Ali Qapu palace, the Chehel Sotoun palace, and the Naqsh-e Jahan Square, making it one of the most celebrated cities in the Islamic world.