What is the signification of the differents letters in the russian last names: "ov", "ev", "sky", "in"

I saw somewhere that "ov" means something like "son of". An "a" would be added for a girl. So the name "Petrov" would means that you're father first name is Petr.
Petrov for boy
Petrova for girl
Am I right?

Does that means that Kovalev = father first name is Koval?
Or Tverdovsky = father first name is Tverdov?
Or Malakhov = father first name is Malakh?

Another question is why not Petrev or Petrin or Petrsky instead of Petrov?


These are good questions!
Thank you!