I usually use a cup instead of the hand, but i didn't think it worked that well with ashes. I thought the wind may have kept half of them, and it wasn't that even. I usually use a coffee cup to spread it, so you can just kind of more evenly shake it out the top. Probably in the morning with no wind and dew, would be the best time. Because you can see the ash coating, I may have just been a bit OCD about it, because the pelletized fertilizer doesn't spread that evenly either, but you don't see the trail of dust as well.
yes and no. It helps with erosion control. but it also focuses on soil health by not disturbing the layers of soil, and reducing compaction with fewer costly trips across the field. It usually takes a couple of years to get the soil biome established. It is a different management technique.
It has a lot to do with the type of nitrogen you are applying and in some cases like corn, how you apply it.