Yup.
One thing the designers were very concerned about was “fizzle” - if a bomb doesn’t fully detonate, it will blow itself apart, spreading the core over a wide area. The Plutonium was so precious that there were plans to encase the bomb in a huge metal enclosure, so that the Plutonium could be captured and re-used if it fizzled. As the project approached testability, the scientists and engineers were confident enough to test it outside of the container.
Yes, but most likely still one hell of a blast, unless you are extremely unlucky.
If you are aiming for 10,000 TONS of TNT, even if you “only” get a couple/dozen/hundreds of TONS, thats still pretty respectable.
And though some fear the radiation boogy man, a few pounds of uranium or plutonium blasted about don’t make that great a dirty bomb.
As far as dirty bombs with normal levels of blast power, they are great for scaring the crap out the town folks, but if you actually want to KILL people, something along the line of chemical or bio weapons are better.
The big problem in 1944-45 is that plutonium was relatively easy to make, but due to the extremely high spontaneous fission rate, it was (still is) only suitable for implosion bombs, which are very technically difficult.
Enriched uranium (Little boy was 80%), is suitable for the much simpler gun-type assembly, but is generally a major industrial operation to enrich, and consequently wasn’t available in nearly the quantity that plutonium was.
Post-war, most bombs were made of enriched uranium (oralloy), due to the fact that it’s easier to deal with, and unless you need an extremely small bomb, the larger critical mass isn’t a big deal. (it’s not pyrophoric, it doesn’t have nearly the number of weird phase changes that plutonium does)