Repeating the question over and over doesn't get you a reply any quicker. It just causes annoyance. This is not a free programming service, but a resource to help users, and I already did that.
To answer your questions without access to the worksheet is difficult however:

1. Your change to the line
Set olApp = OutlookApp("outlook.application") ' this is the line which i tweaked to access outlook.
was inappropriate. The original was correct and sugegsts that you didn't read the comment at the top of the code
'Use the code from http://www.rondebruin.nl/win/s1/outlook/openclose.htm
'to start Outlook
2.The code doesn't loop through the items in Column B. It loops through the messages and compares them with the lastrow of column B. If you want to compare them with all the items in Column B then you need to set a second loop to check each relevant cell.
3. You can define the name of the folder in the workbook, but it has to match the format in the commented out section, which I cannot test without access to your system.
4. I regret I don't have experience of downloading from a link in a message - however https://stackoverflow.com/questions/...-url-hyperlink might help.