Wondering what the benefit is. I am on campaign map 5 or 6 and I never build more than one town. Do you guys have examples of specializations you use?

I'm a newbie :( - trying to fish. My original land had a number of lakes - various sizes, but none have the "splashing ripples" that indicate fish; so I bought lots of land plots...tons of lakes but still no splashing ripples. I tried putting in fisheries, boats, people, ... still nothing. what am I doing wrong?...

Do I build the map in sandbox then save it? And after that where do I find the completed map?

I'm trying to run a long cloth conveyor belt but it tells me I need more resources. Problem is I have a 1000 cloth belts in my town centre. I tried to build a wooden conveyor belt and got the same message again with maxed out inventory. The conveyor belt runs over a river but I've tried moving the belt into several directions but I still get the same message. I've used this map before and I'm on my 3rd build/playthrough. Has this game got bugged maps or sections of maps where strange things happen?...

I'm trying to get my Town Center to level 10 and I'm at 9 and it won't even give me the requirements to upgrade to level 10. I'm in campaign 7 if that makes a difference. I want to get the max base achievement before starting campaign 8, but I'm at a loss to what I need. Am I missing something?...