Second half regarding spread.
Everyone is looking at total numbers and sorting by country. This is a bad approach. No one is transferring patients from Milan to Rome or Aberdeen to London. It needs to be regional.
Looking at many European countries per million capita is much better. The smaller the box we look at the more representative it is of the real difference in case outcomes - healthcare overload (ie., access to ventilators).
The leaderboard today of official cases per 1M people is:
Italy (292)
Norway (190)
Switzerland (158)
S Korea (157)
Iran (151)
Denmark (142)
Spain (128)
...
USA (7.1)
Aside - we all know the USA figure is bunk because we've been testing much, much less than everyone else. On the other hand an early study (non peer reviewed, so take it with a grain of salt) indicates the test used in China and possibly Korea had a very high false positive rate.
We also have to consider concentration of those cases. Italy has 60M people, but most of their cases are concentrated in Lombardy, which has 10M people. So even though Italy on the national level is 292 cases / 1M,
Lombardy is at 872.
So when China was at 17,000 cases on Feb 2, Wuhan probably represented well over half of the totals. That means they were at very similar levels to what Lombardy is experiencing (~9M people in Wuhan). Let's say 750 cases per million people is trip point for fecal matter in the fan.
Growth without quarantine is 30% ish per day. As an example then, the time to fan-poo-scattering based on current numbers for Switzerland is about 6 days from today. :-\
This kind of regional approach is even more needed in the US, because of our size and distribution. The hot spots are in Washington, California, New York...and let's look at Texas.
I arbitrarily assumed that we are testing at 1/10 the rate of Italy. This does not try to estimate "all" cases, just trying to compare our official numbers to theirs.
Then I took the state total population to compare regional cases per 1M capita (mpc for millions - per capita). Then I add a worst case scenario which is all cases in a state are actually in the city listed. The Low number is mpc in the state, the high is cases mpc in the city. By example, this means what if everything we're seeing in Washington state is really just local to Seattle.
I think Washington state is in for a rough week or two. NYC was probably 10-14 days behind, and everywhere else 14-21 days -- exponential growth is fast.
But this makes me think that the rapid implementation of isolation social distancing combined with the end of travel to Europe was good. For example, when Wuhan shut their city down they were seeing 400 new official cases per day. Italy waited one week past that point - when they closed they were at over 1,000.
So be optimistic. We probably jumped on it early enough to not see Lombardy play out here. Except maybe in Washington state.