Thanks for the feedback, I agree it would be useful to have the option to set a fixed price for a project. We actually did some wireframes for this a while back, but we never got around to implementing it. Maybe now would be a good time to look at it again.
What API features are you thinking about? We have a pretty limited API that we built for the iPhone app, but it's growing as we work on the next version of the app. So over time it'll get more of the same features as the website.
You can export to both CSV and PDF. So you can still get reports for your clients, although you'll have to do it manually. We have a pretty limited API right now, built mostly to support our iOS app. As the API grows you should be able to get the reports from it.
Money earned let's you see how much you can bill in a given period, so you can quickly see if you're reaching your goal. We think it's useful despite not accounting for taxes and expenses, and it's a nice moral boost to see the money coming in.
You can filter on projects, clients, date etc. on the Overview page. It's really fast to get filter out exactly the data you need.