1. first off, you are looking at "Max Core Troops" which are your Core units, if you notice it subtracts for every unit you buy. There is also "Force Value" which calculates the cost of your force.
2.I'd have to say that is correct. The game does not recognize 'zero' so, when a designer does not wish to give support points it shows a '1'. (which you can not do anything with).
3.The -00001 represents the 'Zero' mentioned above. This is just programing language and neccessary.
I have been playing with making a campaign also. The only editor is the scenario editor to make a scenario and the 'edit campaign to add scenarios.
the best way to learn is play a few. If you have the full version you can extract the scenarios from the campaign to take a look at how the designer set up their scenarios.
there are alot of trick to making things work, I am learning them as I go. There is not a specific tutorial on making one but, search "campaign" here or on the web and you can get bits and pieces. ***Also basic details are in the Game Manual
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Few free to ask questions anytime.