Some more random questions:

1. Can more eras be introduced? Could I, for instance, create a new "Renaissance" era which would start in 1500 and introduce a bunch of new units?

2. What is the maximum number of units? 300?

3. Is there a maximum size (just pure size, not number of provinces or anything) for the campaign map?

4. Can factions be made to start a campaign as allies or at war with eachother?

5. Can buildings be linked to eras?

Thanks again in advance for all replies.