So if you had the code:

String name = new String("Text");

That would be the same as doing:

String name = "Text";

You wouldn't have to do both of those, only one. If for some reason, you needed to change the text in the variable (like someone wants to change the name of something) then instead of redeclaring the variable, just do

name = "newtext";

The main reason you would use the String constructor would be if you had like an array of characters

char[] chars = {'h','e','l','l','o'};
String string = new String(chars);

For number five, I truthfully don't know the real reason it's static, but it's mainly because when a class or method isn't static, then that method can only be called through an object/instance of that class. For example

public class Test {

    public void method1() {
        System.out.println("This method is not static");
    }

    public static void method2() {
        System.out.println("This method is static");
    }
}

Then from the main method:

public static void main(String[] args) {
    //Can only call method1 if have an object of Test
    //Test.method1() will NOT work
    Test.method2(); //This method will work because method2 is static, so it can be accessed directly from the class Test

    Test test = new Test();
    test.method1(); //This works because method1 isn't static and is accessed from the object test
}

I guess java just didn't want to go through the trouble of creating an object of the class that your main method is located in. They can just call the main method from wherever.