Fred replied:

Which direction is Cape Jervis from Adelaide?
- about 110 kilometres south.
How long would it take me to get there by driving?
- not long at all :)
Where can I find places to camp for less than $10 a night?
- most places charge $4-$5 per person per night.
Does it include facilities like communal kitchens and bathrooms?
- bathrooms (toilets and showers) are standard in all commercial caravan parks, communal kitchens are less common.
What's CJ like in general
- http://www.walkabout.com.au/fairfax/locations/SACapeJervis.shtml

Mike replied:

Ingrid, the drive should take about 11/2-2 hours casual driving from Adelaide. The nearest camping area with the facilities you describe are at Normanville, about 35kms short of the cape, (prices about average for good caravan parks), or Second Valley.The road from Adelaide is first class Bitumen. The cape doesn't have many attractions, apart from excellent views of Kangaroo Island and Great fishing, but it's not far from the outstanding Deep Creek Conservation Park. This park has beautiful bush camping areas. There are also many other features within easy driving distance around the Southern Fleurieu Peninsula. Happy trails, Mike (at Normanville)