Thanks for taking the time to play! Answering your questions:
1. Ending the current delivery counts as a success if you have one or more cargo. Otherwise, you can start again with a new 5 cards. This will be clarified in an update sometime soon.
2. This event counts as a success no matter if you have cargo or not. Will be clarified as well (Lone Adventurer on YouTube had the exact same concern).
3. The Diamonds results are going to have another option - choose none. The problem you experienced makes it impossible to complete a run if you don't already have cargo.
4. Correct. All cargo is dropped-off and you score points. The restocking of one cargo will be implemented as it was an oversight on my end for getting more cargo. Otherwise you are just drawing cards and hoping for a result that provides cargo, which can be brutal.
Thanks for taking the time to provide feedback. I'll be sure to get the update out as soon as I can.