6) Technically, the connection is already present. But one thing to understand is that other than the Indian subcontinent and a few scattered railway networks around the world, Broad gauge is not used elsewhere. Standard gauge is mostly used in Europe.
There is a continuous BG rail connection from Delhi to Zahedan ( Iran) via Pakistan. During the British Era, apparently there was a very slow train from Bombay to Zahedan mainly used for troops. In the present day, with the necessary permits, one can reach Iran from any place in India directly by rail, switch to a Standard Gauge train in Zahedan and head onward to Europe.