Short answers, pulled from the story.
Alfred Kleiner was Albert Einstein's doctoral advisor, or Doktorvater, at the University of Zurich. He held the only physics chair at that university and supervised Einstein's 1905 doctoral dissertation, titled Eine neue Bestimmung der Moleküldimensionen.
Kleiner's main research centered on measuring instruments. In the early 1890s, with students Fritz Laager and Theodor Erismann, he conducted experiments to test whether gravitational attraction could be reduced by shielding material placed between masses. The work was prompted by papers from Louis Winslow Austin and Charles Burton Thwing, and the result was negative: no effect beyond experimental error was detected.
Einstein had a major falling out with Heinrich F. Weber, and by the middle of 1901 was also embroiled in a controversy involving the physicist Paul Drude. He switched to Kleiner and changed his dissertation topic from thermoelectricity to molecular kinetics.
Kleiner, one of two faculty reviewers, gave a positive assessment. He described the arguments and calculations as "among the most difficult in hydrodynamics." The second reviewer, Heinrich Burkhardt, Professor of Mathematics, wrote that the treatment demonstrated "fundamental mastery of the relevant mathematical methods."
After attending a lecture Einstein gave in 1909 on electrodynamics and relativity, Kleiner recommended him for a newly created professorship in theoretical physics. On the 7th of May 1909, the Regierungsrat des Kantons Zürich appointed Einstein as an associate professor, effective from the 15th of October 1909, at a salary of 4,500 Swiss Francs per annum.
Alfred Kleiner was born on the 24th of April 1849 and died on the 3rd of July 1916. He received his doctorate from the University of Zurich in 1874 and served as Rektor, or Chancellor, of the university from 1908 to 1910.