How deep are the existing footings? If you dig below the footings and don't support the soil beneath them with an interior wall, your house could settle a lot or collapse into the basement hole.

How are you getting the dirt out? How are you getting gravel and concrete in? How deep are the water, sewer, and gas lines - are they going to be hanging in the middle of your basement?

Permits required? Are there companies that do this work in your area?

How would I find out how deep the footings are?

I am thinking about using some kind of conveyor system to get the dirt out through the crawl space. I hadn’t thought about how to get the gravel and concrete in. All the Gas/Water/Sewer Pipes are right underneath the floor joists.

I am sure I'll be needing a permit or two; I live in the Seattle area so I know there are some companies that can do this kind of work.

I was talking to a guy at work that said they would probably have to jack the house off its foundation, is that normal?

Jacking the house is one way. The house is jacked up, moved over, the new basement done, then the house moved back.

Another way is to make sure the house is supported, then dig it out as you planned. Once its dug out, you may or may not need a new foundation inside the existing foundation.

I hope I don't need the house moved over, I'll have to find out how deep the footings are I guess