On the subject of the German Uranium, the obituary of Capt. Tibbets in the respected Guardian Newspaper (UK) included the following reference:

"At the end of the month, Little Boy arrived. It symbolised global war. Some of its uranium was from the Congo, confiscated from the Belgians in 1940 by the Germans and snatched from Soviet-occupied Germany in 1945 by an Anglo-American special unit."

Is there any historical record to back this up?

The full obituary can be found at:

http://www.guardian.co.uk/military/story/0,,2204009,00.html