is there any way to save the execution plan in the background (not on SSMS GUI) while the query is running, and then open the plan for review at a...

I finally got it working THIS WAY:

   public void Main()
        {
    string fileText;
    try
    {
      fileText = System.IO.File.ReadAllText(Dts.Variables["FullFilePath"].Value.ToString());
      fileText = fileText.Replace("WTOTA", "TOTAL");
      System.IO.File.WriteAllText(Dts.Variables["FullFilePath"].Value.ToString(), fileText);

     ...

I have tried this way as well but code does not compile...

See the attached too, same.

Public Sub Main()
   '
   Dim reader...

The best I have done so far is adding leading zeros to  entrynumber column (INT) (a different input format than in my post/quesiton).
update MobilityRates Set entrynumber         = Replicate (...

its only because this way it ieasier to output all text fields to text file via SSIS.

yes you are right, they should be.

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[MobilityRates](
    [Area] [varchar](5) NULL,
    [type] [varchar](5) NULL,
    [School] [char](4) NOT NULL,
    [TestType] [char](6) NULL,
    [Grade] [char](2) NOT NULL,
    [Sex] [char](1)...

Sure. Attached is both DDL and DML.
I started doing it via a cursor but it really is not a right way.