uh, excuse me for I am slightly dense and easily confused, so I’ll answer all of your questions.
Germany does not collect any income from captured convoy centres. Imagine trying to reclaim all that sunken cargo, completely unviable.
All you really need to remember about transports is that once they unload their turn is over. This also applies to when a transport “moves” within one sea-zone; once it’s load of troops is landed the transport can’t turn around and pick up more.
The allies don’t get paid if they control the Middle Eastern territories. They are merely there to serve as a penalty to the allies if Germany captures them.
Yes, you must roll for each column seperately. Otherwise one could rack up an amazing number of hits by designating all of his ones as being infantry attacks, all of his twos and threes as being fighter and tank attacks, and so forth.