Since I asked myself the same about your first question, I will watch this thread to see if someone has an answer to that.
To question 2):
As far as I know, there is no way. When you create the campaign, you add the ships that are used there or combine your mod with another one with already existing models. So as long as no one "upgrades" the campaign and its mission/model files, there will always be same models. Theoretically you could go and open the mod to replace the models by hand, but this would mean almost every time you will also need to change the table files for the new models. And their might also be balancing issues in the missions if, for example, the new model has much more weapons points. So you would also have to take care of that.
TL;DR: There is no automatic way, you would need to do it by hand.