the person who wrote the english version of the above mentioned treaty, who was he?
A British Royal Navy officer and the first Governor of New Zealand.
William Hobson
Captain William Hobson (26 September 1792 – 10 September 1842) was a British Royal Navy officer who served as the first Governor of New Zealand. 
who wrote the english version of the treaty of waitangi William Hobson, with the help of his secretary James Freeman and the British Resident James Busby. when was this treaty first signed? 6 February 1840. and by whom? Representatives of the British Crown and Māori chiefs from the North Island of New Zealand. what is its importance? It established a British Governor of New Zealand and gave the Māori the rights of British subjects. what are the principles of this treaty? One of the principles deals with  the exchange of sovereignty by the Māori people for the protection of the Crown.
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William Hobson [SEP] Introduction
Three months later, Hobson proclaimed British sovereignty over the islands of New Zealand. He also selected the site for a new capital, which he named Auckland.