Ug
How fat is your wallet? If it were me I would tear it all out if I could afford to. That stuff is called Masonite (one brand). There were lawsuits. check
http://www.masoniteclaims.com/ (unsure if that's an official site, don't get scammed)
You may be able to side new right over. Stucco or vinyl may be an option. Don't put on synthetic stucco (also lawsuits)
Good luck