Don't do carpetsDon't do dishwashersFor rentals unless they're premium units I prefer "builder grade appliances"I won't touch an AC unit.... but if it's required you can get them cheaper than what you have quoted.I would do the roof myself and save the $$ but that's only if you like to do that kind of work.Personally I take 5% of each monthly rent and put it into an account that I eventually use to spend on small expenses that require maintenance.

A deal is a deal.Otherwise, obvious things to consider are two sets of closing costs, two sets of insurance premiums and property taxes, etc. if opting for two duplexes over one fourplex. 

What sort of risk premium is typically applied to this sort of practice?

Individual cases aside, if your risk is too much of the probability (such as East Rift Zone 1), you eithth have grandfathered policy, uninsurable or premium is astronomical.  

We purchased for 135,000.00 with a 10% buyers premium( SEV 79,900) We  need to pay for within 30 days so we will pull money out of his 401K (He is 62), and then replace within 60 days, as long as the financing is on time, to avoid paying taxes. 

@Simon Lopez most policies can only go to $1M in Personal Injury, hence the need to buy an Umbrella policy.Check around for a lower cost Umbrella as there are options out there with premiums closer to $350-$400 for a handful of homes.

Seller's title company is going to waive title premium and charge fees.

The margins are stripped off a lot of those deals since the local flippers are often very willing to pay a premium just to get a deal locked down, so keep that in mind. 

The government has subsidized these food premiums for years, but every year one hears rumors of the subsidy being lifted. this is the REAL scare of purchasing any property that is not on stilts.  

Those who can insure your home take wildfires into consideration and offer high premiums due to the risk.You should Google insurance companies (not necessarily "big bear insurance company") and contact providers to see who will come out the cheapest.