“var” variables, "this" variables and "global" variables - inside a JavaScript Constructor

After my last question, this one is more accurate for me:

example:

function Foo() {
    this.bla = 1;
    var blabla = 10;
    blablabla = 100;
    this.getblabla = function () { 
        return blabla; // exposes blabla outside
    }
}
foo = new Foo();

what I understand now:

this.bla = 1;     // will become an attribute of every instance of FOO.
var blabla = 10;  // will become a local variable of Foo(will **not** become an attribute of every instance of FOO), which could be accessed by any instance of FOO - only if there's a method like "this.getBlabla". that's a "closer" ?
blablabla = 100;  // will define a **new** (or change if exist) global(window) variable.

Do I understand correctly?

Also - if I include var blabla = 10; and the getblabla function that uses it in the contractor, then for every instance of Foo("foo"...), there will be saved a Foo contractor function in the memory that includes this "private" variable. or will it be the same Foo function as place for the private variables - for ALL instances(like "foo") of Foo?