Business analysis, so you build the right thing before building it well

You can, and for a small, well-understood change it is often the right call. For anything substantial it tends to be a false economy: the cost of building the wrong thing is always higher than the cost of establishing what the right thing was.

Possibly not. If you can state the problem, the process, the constraints and how success will be measured, you may have already done the analysis. Where it usually helps is when different parts of the organisation would answer those questions differently.

No. The output is a brief you own. It is deliberately written so you can take it to any supplier and get comparable quotes — which is also the fairest test of whether the analysis was any good.

Usually weeks rather than months, and it should be scoped tightly. Analysis that runs longer than the enthusiasm for the project it was meant to enable has defeated its own purpose.

Then it has paid for itself many times over. Some of the most valuable engagements end with a recommendation to change a process, buy a product, or do nothing at all.

The people who do the work, not only those who manage it. The gap between how a process is described and how it is actually performed is where most requirements go wrong.