1) As for how many trees are cut down each year, the 2005 report concludes that primary forest area was reduced globally by 60,000 square kilometers per year. It’s impossible to get an accurate count as tree density in primary forests varies from 50,000-100,000 trees per square km, so the math would put this number at 3 billion to 6 billion trees per year.
2) As for what purpose this logging is for, 2007 report provides statistics on global production and consumption of woodfuel, round wood and sawnwood. It estimates global production at 1.7 billion, 1.6 billion and 421 million cubic meters respectively with comparable volumes consumed globally. ( Source: http://understory.ran.org/2008/04/22/how-many-trees-are-cut-down-every-year/ )