1) Yep, 18 between frigates and cruisers.
2) The two pages are for frigates and cruisers, that's how it differentiates 
3) Yes and likewise the pages are for logistic and tactical buildings.
4) Until you try it? Hard. As a general rule of thumb, the more weird you make it the more likely the AI is not to like it. Most straight forward stuff is just fine.
5) Yes, each ship has its own cargo capacity for carying the stuff.