Size - I tend to build as big as possible. My reasoning is that if fields were very small, there would be lost work time between planting and harvesting while waiting for the crops to grow.
Farmers - With only one farmer, there will likely be crops lost to freeze as winter begins. The more farmers you put to work, the faster they will harvest the crops and thus produce more crops.
If your goal is sheer food production, you should max out farmers on every field.
If your goal is maxing out efficiency per worker, you should have one or two farmers per field - they will hit their maximum amount of crops planted and gathered even if some go to waste.
If your goal is maxing out efficiency per space of land, you should max out the farmers on every field to reduce the need for more farms.
Roaming - Farmers are "assigned" to a particular field, split up evenly if you do not micromanage the number of farmers per field. If farmers on one field die or are reassigned to another job, farmers from other fields will come over to even out the numbers to each field.
Fishing dock - If you want to further micromanage your farmers every year, you can re-assign them to other tasks. Without any intervention, they will act as laborers during their downtime. Personally I think it's too much effort to go to that level of micromanagement, but if you really needed extra production in a certain area it wouldn't hurt, so long as you get the farmers back to their fields in time for spring planting.
Regarding your comment on a single farmer able to handle a field by themselves - this could be a number of factors, size of the field, quality of the tool, level of education, the farmer could have just eaten just before it was time to plant, harshness of the weather in early spring or late autumn. Leaving it up to these factors sets you up for large swings in food supply.
Despite what appears to be common belief here, squash are the most resilient to cold, being able to go down to 25f. From the resource files:
Squash:
- float _growthTemp = 55.0;
- float _growthTempRange = 30.0;
Pumpkin:
- float _growthTemp = 60.0;
- float _growthTempRange = 20.0;
However, it also appears that snow kills all crops, regardless of temperature tolerances.
Best Answer
Yes, crops grow at different speeds and have different tolerances to cold temperatures. This is unrelated to the purpose of the calculator to which you link.
The calculator highlights how many food units can be produced (total and per laborer) in an ideal growing year for any given crop with a particular sized field. Also given that pestilence can ruin fields in an area for a particular crop, it is important that fields be crop agnostic. So it helps you create fields that are a good geometry for the available land.
That said, most years are not ideal. If you're doing things right, you should either be bumping up against your food quota during harvest time or preemptively squirreling food away in your trading post(s). In a fair year, your bean crops may be completely harvested to ideal quantities and when the pumpkin harvest comes along some are left to die on the vine due to your quotas. In a year where temperatures dive early, you could easily loose half your bean harvest, and be saved by your squash and pumpkins. The vagaries of weather are outside the scope of that calculator. Growing a variety of crops is a good way to cope with what the game throws your way.