The 1st one is most critical

Using the air-tight method mentioned, the cost for treatment should be the same regardless of the size and area affected. However the repair cost could be quite different. If the damage is severe, the life of the structure could be vastly reduced.

So you want to know what are exactly the areas affected and need to break the wall and repair.
I would pass if things turn out to be bad. Frankly it will not easy to confirm the internal damage without breaking out the walls to some extent, so there will be some risk there.