Is this the Norwegian one or is it another one in Germany?

The Germans had two heavy water plants up and running during the war. They had the well known Norsk Hydro plant in Rjukan, and the I.G. Farben plant in Leuna (near Berlin). Both of these were bombed out of commission.

"Pineapple sized piece" of what kind of uranium?

The quote from Heisenberg was about the quantity of enriched uranium he believed was necessary to initiate a nuclear explosion. The bomb itself would obviously be larger than just the uranium content alone.

it is evident that Germany had enough unprocessed Uranium in 1945 to produce a bomb; the hard bit would be constructing a place to refine it all

The German scientists had been working on the process of uranium enrichment since 1941. They invented several different methods of achieving this: Through centrifuges, isotope sluices, and mass spectrometers. All of these devices were actually in operation by 1944. The problem was that the Germans simply did not make enough of them, and as a result, they were only able to result small quantitys of uranium before the war ended.