This question is a bit like blind men describing the elephant.
Absolutely.
2) Technology is key. I see the atomic bomb being test and deployed in the 1930's. By the late 1940's, everyone has them.
On what grounds? Would the lack of WW1 make Einstein, Meitner, Bohr, Fermi or Planck be smarter or think faster? By that much?
OTL, 1939 only saw the proof of nuclear fission actually EXISTING!
Now without being at war, which nation would devote that much capital into developing a bomb which
a- might not work at all
b- if it works, might destroy the planet instead of just a city
So, even in OTL's WW2, only the USA had the capability to actually pull that through. A four or five way nuclear race as in TL-191 is imaginable in peace-time, but it would work in slow-motion compared to the Manhattan project.
My idea for a realistic timeframe would be that closely around 1950, the first nuclear weapon is tested. First possesion of a nuclear bomb? Probabilities are: 50% Germany (frankly, the German scientific position in this field was amazing, especially if not weakened by emigration), 30% USA (very much depending on the political will to undertake the project), 15% Great Britain, 5% others.
3) Demographics. Demographics are destiny. Without WW1 and the follow up we have 300 million or so more people of European decent and AT LEAST 300 million fewer non-European descent.
I love demographic views at topics on that forum. But please calculate that number to me. If you had said 100 million, I would have bought it at once. 300 million seems totally exagerrated to me.
Example: Germany in 1910 had close to 65million inhabitants. For my model I assume the population growth of the period of 1925-33 (4.73% in 8 years) as typical for the period of 1910-1950. I round it up to 5% even.
1918: 68,25m (instead of 60.8 in 1919 OTL)
1926: 71,66m (instead of 62.4 in 1925 OTL)
1934: 75,25m (instead of 65.4 in 1933 OTL)
1942: 79,01m (in 1914borders instead of 79.4 in 1939 OTL - as Großdeutschland!)
1950: 82,96m (instead of 68,23 in FRG/GDR combined)
Since then, I would assume a population growth consistent with OTL. It SHOULD be even lower as this peaceful Germany would be richer and go through demographic transition earlier, also not have a post-WW2 baby-boom. However, this is probably offset by not having the very very low birth-rate in the Communist GDR.
So....Germany in OTL 2012 has 81.843 million inhabitants, that includes millions of immigrants, a tendency which might or might not happen ITTL. A rise by almost 20% in 62 years.
For the sake of argument, I allow the peaceful Kaiserreich a 30% rise.
That means 107.9 million Germans in 2012 ITTL.
That is an extra of 26 million Germans ITTL. Where are the other 274 million white people coming from? Take into consideration here, that Germany demographically suffered quite hard in both world wars. Not hardest, but it was hit more significantly than e.g. Britain.