No, fuzzing is not a requisite for exploit development.
as google tells me that it is not possible to reverse engineer a C/C++ .exe file back to source code, that you only get assembly?
Though it is technically true that the exact source code that a binary was compiled from cannot be recovered via decompilation, this also somewhat misleading, as your ...
This question is better suited for https://reverseengineering.stackexchange.com/questions/.
Is there a comparison between Ghidra and Ida?
Yes there is. One was made by Jeremy Blackthorne and Alexei Bulazel at the Infiltrate security conference 2019.
video of presentation (1 hr 17 mins)
slides used in presentation
github repo with all materials