Can we set different types of parameters & return-types in main() method"?

Yes. The Main() method may easily be played around with by developers by passing different parameters and setting different return types. See the code below, that demonstrates different ways the Main() method may be implemented:

C# Example
(1)
public static void Main(string[] args)
{
 //NO return type, the argument is an array of strings
}

(2)
public static int Main(string[] args)
{
 //Return type is int, argument is an array of strings
}

(3)
public static int Main()
{
 //Return type is int, NO arguments
}

(4)
public static void Main()
{
 //Return type is void, NO arguments
}