will older software from 10.6.8 function on new mac with newest OS?

I have a friend who is concerned that when he moves the contents of his older snow leopard iMac to a brand new iMac his old trusty apps like Photoshop Elements and his Entourage email program will not work on the new machine. I've advised him to go ahead and get the new iMac and change to a new email system and use Fotor or some other image editing app. The main questions are - can he move his extensive address book from Entourage to a new email app. and will any of his older software work on a new machine? Please advise. Thanks.