Moving dirt in crawlspace in house with daylight basement?
As I understand it (second hand from friends in construction) you must maintain a 45-degree slope from the top of the footing (the footing must be buried according to frost depth rules if your crawlspace gets below freezing), whether that be a retaining wall or a dirt slope, you can't cut into that 45-degree or you risk undermining the foundation.  A soil engineer might tell you differently depending on your soil type.  Google "bench pinning" and "underpinning" for two ways to support a foundation when excavating nearby.  there are also pile methods that support a footing on rammed pilings, but that method is usually used when the foundation has already gone out-of-level.