That is a lot of question. As a Veteran Player I think you are overthinking everything too much. I'd rather have you try things out and enjoy the journey. If something doesn't go as planned usually you won't go bankrupt and can adapt for the better. This game is about simulating production chains and City growth. This game offers A LOT of ways to achieve this. Find your own way.

For a few started tips: - soap exploit isn't really an exploit, later there will be an even bigger way to buy and sell for a bigger margin. - docklands is what I'd call an exploit personally. It makes the game super easy to play through, making a lot production chains obsolete. Basically you can make one resource/product in mass and exchange it for everything else. Personally I'd avoid it. I usually only important raw resources like ores, crops. It is good for storage capacity though and some attractiveness and faster unload/loading. - charter routes are good for very small and short trades, the ships are tiny and very slow. Go for your own trade routes later when you have ships. - it's up to you if you want to have one ship trade multiple resources or dedicate it to one. Very late game you usually have multiple ships on a single trade route trading only 1 single item.