[SCoach]

1. No.
2. Yes.
3. Power loss is cumulative, but generally, it comes from the fact that over time, engines lose compression due mostly to wear on the rings. While its' not an overly complicated thing to change out on a common US V block engine, it is exacting work.

There are some relatively simple things that can be done to restore that power once the engine is out of the car, or the head is removed.

Think of the engine as an air pump. The more efficient the pump, the more power it will make. Seal it up super tight, and that bad boy is going to get the most it can out of it's displacement.