I particularly liked how flexible her thinking was on billing. "Hourly, with a cap" is one good way to do it; we tend to do "flat rate, fixed schedule" to similar effect. My only critique is with using "hourly" as your time quantum. Hourly sucks. It's probably some kind of standard in design, but even if you're a designer, I recommend pushing it at least to "daily".
Has anyone else here obtained a "line of credit" (say from a bank)? Do we think she just means "get an Amex card"?
Two other points I'd add:
* Incorporate: LLCs are (very) cheap and absorb most of the risks that are most likely to bankrupt you or take your house away.
* Get an accountant. Less cheap, but almost certainly cheaper than doing your taxes yourself; in several of the last 7 years, my accountant has made me money.