I have been working in the US since April 2007 on an L2 visa (and EAD card). Am I considered a resident or non resident for tax filing purposes?
Also if I have received rental income from a property abroad what forms do I need to complete to declare this?

You are a dual-status alien.

The rental income received since April 2007 IS subject to U.S. taxes, but you are also eligible to claim all of the deductions associated with such rental property, so it is likely you will show a paper loss on your dual-status return for the rental property.