New Zealand welcomes and encourages foreign investment from all countries, without discrimination. The general policy is based on the premise that proposals should be approved unless good reason exists, in terms of the legislative criteria to decline an application.
Non-residents can participate in a wide range of economic activities in New Zealand, directly or indirectly, through various mechanisms including companies, partnerships and trusts.
The Overseas Investment Office administers the New Zealand Government’s foreign investment policies. The core work of the office is to assess applications for consent from foreigners who intend making substantial investments in New Zealand.
Under the new Overseas Investment Regulations 2005 an overseas person will require consent to acquire
Land that exceeds 0.4ha (4000m2) and includes or adjoins the bed of a lake.
Land that includes the foreshore.
Land in excess of 0.2ha that adjoins the foreshore.
Land that is 5ha or greater.
Land that is greater than 0.4ha and adjoins or includes heritage, conservation or historic areas.
Business or non-land assets worth more than $100 million.
The New Zealand government promotes direct foreign investment primarily through two bodies - the Ministry of Foreign Affairs and Trade (MFAT), and the government's trade promotion agency, the New Zealand Trade Development Board (TRADENZ). Other government agencies, such as the New Zealand Tourism Board and the Ministry of Forestry, are also active in promoting foreign investment in their respective sectors.
Check out http://www.linz.govt.nz/overseas-investment to answer all your questions.