No work begins without a signed fee agreement. You know the financial framework of the engagement before it starts.
For an executive, an unpredictable fee is one more risk. The firm therefore treats the financial framework the way it treats the case: in writing, in advance, without ambiguity.
Every engagement starts with a quote, continues with a signed fee agreement, and is invoiced in detail. Amounts depend on the nature and complexity of the matter: they are specified at the first meeting.
The method depends on the engagement; it is proposed and explained at the first meeting.
Amounts are specified at the first meeting, according to the nature and complexity of the matter, and formalised in a written fee agreement.
The financial framework is discussed from the first exchange. You then decide, fully informed.