You can retrieve any fields that are exposed to the API you are using. The Rest API looks to allow you to pull any of the fields, but we have not worked with it yet. We have worked with the SOAP API, and there were a few fields we could not access.
In the admin section, go to field management and select export field names right below the fields tab. This will list out all the fields available to each of the APIs for you.
.png)