How easy or hard is it to change the air suspension over to struts?

Depends on how competent of a mechanic you are... My air suspension leaked profusely ( 16 years old ) went on line & ordered shock / strut kit - came with step by step instructions & numerous videos available on you tube ( highly recommended to familiarize yourself with task - watch the professional shop ones). They said about 4 hour job , took me 5 hours , I had to cut off one bolt in front air strut, otherwise , just a one wheel at a time project in a house garage. Get strutmaster if you are going to keep the car.