Project management by people accountable for the outcome

Often you would not. Where we are usually asked to help is when a project spans several suppliers, needs technical judgement to challenge estimates, or has reached a point where an outside view is more useful than another internal one.

Whichever suits the work. Fixed regulatory scope with a hard date is genuinely better planned up front; evolving product work is not. Being dogmatic about either is a stronger predictor of failure than the choice itself.

By making the cost visible at the moment of the request rather than absorbing it quietly. Most scope creep is not unreasonable demands; it is reasonable additions whose cumulative cost nobody was tracking.

Then the first job is an honest assessment of where it actually is, which is usually different from where reporting says. That can be uncomfortable, and it is much cheaper than continuing on a plan everyone privately knows is wrong.

Less than running it yourselves, but not none. Decisions still need making, and a project manager who never needs anything from you is not managing your project.

Yes. Managing delivery from other suppliers is common, and being independent of the build sometimes makes the challenge easier to make and easier to hear.