[MetaCosm]

1) Nonsense, you raise your rate as you prove yourself, as someone who bills at $185+ -- clients aren't idiots. They understand that if you can do it in 1/5th the time and cost 3x the money, they are still saving money. Clients can do basic math. The only time you need to worry is if you can't prove your skill (bad references or new to market).

2) No professional ever uses the phrase "hourly" -- it is always T&M (Time and Materials). Most professionals with enough experience work in 'standard days' or 'standard weeks' on longer contracts. Last contract I did was billed at 7700 a week, no hourly accounting.

... some of what you mention (variable bill adaptation) is tricky as hell, and on FFP (Firm Fixed Price) contacts, it can be outright illegal without clients signatures at every change point. This is a reason home renovators always have change request forms with them.

~ Beyond all that, FFP puts you at odds with your client, you want to fuck them by charging as much as you can and working as little as you can -- they want to bleed you for as many hours as they can while keeping you bound to the initial contract. Nothing like starting a contract as sworn enemies.