And get their opinion. We can't diagnose this if we can't see it. Our answers here would only be a guess. The abatement contractors would tell you up front what you need to do, or not, and give you a good idea of what you're up against. Then decide whether you want to do the tear out yourselves. In my opinion, hire the experts. The difference in money is worth the effort, risk to health, and pain in the neck factor of disposal, not to mention licensing and permits.