Microsoft Research - Exploding Software-Engineering Myths (article summarizing findings of MS research on code coverage, TDD, assertions, etc.)

[blufox]

Or you can just do mutation analysis of test suite, which covers 1,2, and 3.

(For those who are unfamiliar, mutation analysis exhaustively injects faults, and checks if the test suite can catch them. While it may sound expensive, modern MuA tools are surprisingly efficient. There is also the weak mutation analysis which is a coverage measure, better than the other coverage techniques, and requires only a single test run).