Excel 2003 :: Autopopulate Data From 1 Database To Another?

I have inherited a number of databases in work (running Office 2003). It has quickly become apparant that a vast amount of work is duplicated and so i am trying to cut down the data input and therefore the possible errors.......

I have narrowed most of the work down and now have a major worksheet (is that what you call a complete Excel file) named "master database" and several over minor files....

Currently what i am trying to do is to get one of the minor files to auto populate an area of the master database. I will try to explain it below...

1. Minor database has 2 columns with data i require to auto populate the master database. (1 column (B) is called 'off', the 2nd column (C) is called 'on').

2. A number will be inputed manually into either 'B' only or 'B and C' columns, depending on the criteria of the job..

3. The criteria of the job is dictated by column (Z) where the text 'A' or 'ATL' is inputed

4. The master database i would like to add up the numbers inputed as a total from columns 'off' and 'on' and place them into seperate columns 'E' and 'G' of the master database.

5. IF column (Z) shows 'A' then only column (B) 'off' is to be calculated and put into the master database at column (E)

6. IF column (Z) shows 'ATL' then BOTH columns (B and C) 'on' AND 'off' are to be added together and column (G) populated on the master database.....

To make mattters more complex. An expiry date is shown on the master database at columns (D) and (F).
IF column (E) does not exceed 12 by the expiry date, i would like the cell (D) to turn red
IF column (G) does not exceed 10 by the expiry date, I would like the cell (F) to turn red