Their seems to be confusion here regarding the Strata insurance because the Strata insurance covers both common property AND lot property. It covers basically the same as a Home Insurance policy does on a freehold property (plus other items).
My opinion is that the Strata are responsible for all the repairs to the roof and the damage done to the lot property (maybe with the exception of any contents) including the built in wardrobes (fixtures and fitting), repainting the ceiling.
Most of this will be covered by the strata insurance but what is not is up to the OC to pay for.
Also with regards Waterboy the floorboards are def part of the structure and so are covered by the Strata insurance but as their is no strata insurance the OC are liable for the full cost.