Sorry about your personal loss. The settlement is tax free to you because it is compensation for personal physical injury. However, if any part of the settlement is for punitive damages, those are taxable.
Depreciation methods that allow faster write-offs than straight-line rates in the earlier periods of the useful life of an asset. For example, in the first few years of recovery, MACRS allows a 200% double declining balance write-off, twice the straight-line rate.