Hi!
1- These options are not about cohesion. They are about supply (so you do't have to go bvack to port to resupply). The cohesion loss may be caused because you use offensive porture on the boxes. DOn't do it. Put them on deffensive and you will not loss cohesion.
In the boxes posture does not mind. The system used is different. Hunters will attack runners adn raiders will attack transport even on defensive stance.
2- Never experienced it

Maybe you are mistaking one units for others as you ordered a lot at the same time?
3- Yes,this is a know quirk, but not too important.
The problem is that Ft sumnter/Pickens areas have high USA loyalty so they give you some info on the surrounding areas even after taken by the CSA. This would be right on a normal area as the population could send info north, but on a fort there should be no unloyal population (the cook maybe? :niark

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Mayeb Gray Lensman could add it to his long "to do" list
Regards