Well the reason you can't just have 1 ideal ratio Lousia is because everyone makes their settlement unique to the next and it depends on what you want to optimize or what your current focus is. The ratios are directly porportionate to the details of production time when you click on a building, leaving no room for error other than the fact that overall time also depends on how close your building is to a storehouse or your mayors house as this also directly affects production times. Thanks for doing this Arad, now I can just tell them to go check on forums if they can't crunch the numbers in building details :P
As for farms to fields it doesnt matter much altho personally I do at least 2 fields to every 1 farm so if I'm offline for an extended period and 1 field gets exhausted my farm has a backup that it can still farm. You can do however many farms to 1 field but it will use up more licenses and burn up your fields that much faster. Same as with wells for breweries and bakeries. The key thing is to keep an eye on your amounts so you aren't running dangerously low.