Sunrider, I did this presentation on Genworth MI Canada that answers most of your questions https://onbeyondinvesting.com/blogs/blog/ira-sohn-2018-investment-contest-finalist-short-genworth-mi-canada
Couple quick points, they get paid upfront in one lump sum payment so there isn't a steady flow of premiums coming in. They also recognize most premiums as revenues in first 5 years, so they are really susceptible to slowing market as insurance written decreases.
The pay the bank upfront for lost interest, they then take possession of the house and sell through power of sale to recover their losses. So losses are taken immediately, and they have to hold, maintain, repair houses when a bankruptcy occurs, which is an expensive process.
Mortgages are recourse, but that matters far less in recovery than people think (like companies get 52% vs 50% recovery due to recourse). The reason is once a person loses their house its hard to get blood from a stone, there is also the PR implications of being aggressively collecting from people in dire straits.
Hope this helps. Let me know if you have any further questions.