Customization & which package to purchase?

[Marco van Herwaarden]

1. vBulletin by default also allows for a threaded mode.

2/3. This would need a modification. You might be able to use vBulletin Project Tools Open Source as a starting point.

4. Not really sure what you want to implement, but it is possible to use the vBulletin authentication/permission system on external php-pages. Although less common it is also possible to use an external authentication for vBulletin, but that would also require custom coding.

5. All data is stored in a MySQL database and can be used in queries.

vBulletin comes with a plugin system which makes it easier to extend/modify default features/behaviour without the need to edit source files of the core product. See also Plugin System

You would probably have no need for a CMS, so the forum only product should be the ebst license type for you.