Hi, so I just felt like adding my two cents here. I've been raising silkworms since 2020. I've also read alot about the topic. Mating can be from several hours to about a day. I've seen both. I've read that a female can give between 300 - 500 eggs, although other sources have cited different numbers. I've found it to vary from female to female. Ones with bigger abdomens are usually carrying more eggs.
I've always heard that the eggs take between 7-21 days to hatch, and while mine usually fall within the latter part of this range, I've also had some exceptions such as ones as old as two months hatching. If your eggs turn black three days after being laid, they are in diapause and should be put in the fridge for about two months to simulate passing winter in their dormant stage. However if the eggs don't turn dark in three days and you see a bit of orange with a yellow spot in the middle, and then eventually darkens, well these do not go in the fridge and will hatch right away. Trust me, I learned that the hard way.
For difficulty, personally I would say that the first year is the most difficult because even if you have done your research, there's still more to learn from experience. It's especially hard if you end up with sick worms. I find it easier now to manage them, and it takes less time, but they take more work than other caterpillars because they depend on you entirely.
Here's a picture of a female silkmoth with her freshly laid eggs:
