what is the ideal life of a roof before making a purchase?

[Chase Maglangit]

Aloha everybody, 

I'm recently under contract for a property  and the roof for the property is questionable. The inspection report that I received was before the renovations/ corrections were made ( was I supposed to get a post inspection result?)  The back of the house there's a section with a slight slump (according to the pictures). Another major concern to me is the foundation seems to be compromised also with cracks and missing blacks under one of the corners of the property. Also the chimney looks old and compromised according to the exterior photo and the attic photos.  I've never received photos of the corrections. Can you folks please share thought and or recommendations.  I also already gave my earnest money to the title company.  What if I'm not happy with the inspection report can the turnkey company take a portion or all of my earnest money?   I feel like that isn't right if I'm not entirely happy with the product.