Sabrau Jack

Hi all. I am possibly looking to get my first Subaru Im looking at an Impreza around a 2007 the newer shape. In a 2.0L few questions if you don't mind. Is there anything I need to look out for when viewing to buy? when do they need the timing belt changed? What is classed as high mileage and should keep clear of over 100k? is there many common problems with them? thanks for your time jack