How many simulations are we running? Is it feasible that we could run enough to actually make a good decision?

I'm assuming that the AI will be allowed to FOOM and take over enough of the universe to run enough simulations. If that's still not sufficient, we can make it more likely for the AI/human team to find a good outcome, at the cost of increasing complexity. For example allow the humans to tell the AI to restart another set of simulations with an embedded message, like "Last time you did X, and it didn't turn out well. Try something else!"

What moral weight should we give to the inhabitants of those simulated world, especially those in worlds that will be substantially worse than our own (ie Negative Singularity), relative to the people that we might save by increasing the chance that a Singularity will eventually be positive?

Have humans monitor the simulations, and stop the ones that are headed in bad directions or do not show promise of leading to a positive Singularity. Save the random seeds for the simulations so everyone can be recreated once a positive Singularity is established.

How do we ensure that we don't just select a decision process that creates desirable outcomes several decades into the future, but fails a century from now?

Do you mean like if a simulation establishes a world government and starts to research FAI carefully, but a century after it's released into the real world, the government falls apart? We can let a simulation run until a positive Singularity actually occurs inside, and only release it then.

Your proposal is interesting, but there do appear to be a number of substantial issues with it that I would like to see answered before this proposal is implemented.

I originally wrote down a more complex proposal that tried to address some of these issues, but switched to a simpler one because

1. I didn't want to focus too much attention on my own ideas.
2. There are a bunch of tradeoffs that can be made between the complexity of the proposal (hence implementation difficulty/risk) and chance of success if the proposal is correctly implemented. We should probably leave those decisions to the future when the tradeoffs can be seen more clearly.