first question

static void Main(string[] args)
{
    // create a list with 2 elements
    var q1Items = new List<string>()
    {
        "Foo", "Bar"
    };

    // aaahhh LINQ will deffer the execution of this query until it's value is actually used (i.e. .ToList())
    var which = q1Items.Where(x => x != "Bar");

    // which didn't run yet
    q1Items.Add("Baz");

    // q1Items has 3 elements now. the actual where query will happen on the next line
    var nonBar = which.ToList();

    // nonBar has 2 items now ("Foo" and "Baz")
    Console.WriteLine(nonBar.Count); // print 2
    Console.ReadKey();
}