Hi, there have been a few threads on the Great Man Theory; while you're waiting for direct answers to your questions, check these out:
What is Great Man history? What are its "pros and cons"? featuring /u/LordHussyPants and several others
What makes Great Man theory rock/suck? (i.e. What are the major current historical interpretive practices?) featuring /u/BeondTheGrave and /u/plusroyaliste
Why was the Great Man Theory no longer emphasized? featuring /u/medieval_pants
Test case: Hitler META On Adolf Hitler, great man theory, and asking better historical questions featuring /u/commiespaceinvader
Test case: Science Science history and the Great Man Theory featuring /u/Talleyrayand
Test case: France What's the appeal of the Great Man Theory in any of its forms? Or having one man or group with the "right ideas" against all foes? featuring /u/DonaldFDraper and others
These posts have all been archived by now, so if you have any follow-up questions for any of the users, just ask here and tag their username to notify them.