The latest version of "survey" is known informally as "complex survey" and currently is version 0.3d1. It is located in /contrib/packages, not /packages, in the OpenACS 5 distro. It advances "survey" 0.2 importantly in its support for branching and paging.
Here's an informal pseudo-ERD of the package (ok it's not a real ERD but a quasi-pseudo-hybrid-UML-ERD, but it's more compact and hopefully captures the meaning). The OmniGraffle file from which this image was exported is available here.
To follow: discussion of strengths of model and where it needs additions/augmentations.