in the 1980s and still own one. Batavus though more popular for their mopeds is a huge mfg of bikes in Holland. Their factory had a large automated assembly line that could assemble prepared tubes into lugs and braze them using a little slug of filler inserted during the lug prep. They powder coated their cheaper frames then. They also maintained a small hand crafted frame shop inside the factory which created their top-of-the-line Professional model and the model below that. The Pro used Columbus SP/SL tubes and I believe they were partial to Dura Ace dropouts and fittings at the time. We ordered ours with Camp dropouts but they came with the Dura Ace shifter bosses - go figure. (I modified a set of Campy shifters to work with those bosses). The frames were of high quality construction but the finish details that set apart the American and some Italian frames were not as good.
To answer the 2nd part, Their bottom brackets all had English threading.