Compare And Update Selected Data On Two Sheets

Each monday i get a new price list from our supplier. My job is to compare this list with ours and update if neccesary. The reason, why I'm writing here is simple -I need to automate the process. Since their and our pricelist is somewhat different, it's only possible to use selection comparison. So, I need something that can do this:

1. First I open those two files and make a selection on both of them (like all the apples on the supplier list and all the apples on our list)
2. Push a button that executes a code
3. The code compares a value in the first column
4. If it finds a match, compares the data in second column
5. If data is same, color the cell (or the text) lets say yellow
6. If data is different, update field in our pricelist and color the cell (lets say red), so I can find and recheck it later
7. If the supplier has a _new_ product, the code will insert it somewhere in our list. Doesn't matter where, it may as well be a new sheet
8. Compare the next cells in selected area