[gabrielgoh]

good questions! (author here)

I've had a hard time trying to find hard figures on these numbers, and am trying to steer as much from speculation as possible.

Your second observation is a very good one. This is true, e.g. for the default intervention. Adding initial infections has a similar effect to waiting, and delaying an intervention can have a tremendous effect (at least according to the model) on the course of the epidemic