Conditionally require user to complete a content type based on answers from other content types?
Interesting question (challenge), with quite some background info (so well documented question). It seems that at its core, this is the key challenge you need to address:


  Finally, I would need a dashboard to keep track of what content types are required, pending and have been completed - then once all of the required supplemental content type questionnaires are verified completed, allow the user to submit a finalized profile.


Here is a "rough step by step" answer you asked for:


Use the Flag module to introduce a set of flags related to your business content type. That set consist of 1 flag for each extra questionnaire (content type) that might possibly be needed. E.g. 1 flag related to "foreign operations" and another flag related to "employees".
Use the Rules module to automatically set the appropriate flags to indicate that some related content type is required, but still missing (or not fully completed yet).
Whenever such related content type gets completed, you "unset" (automatically, via Rules) its corresponding flag.
Should you want to implement some review process (as per your "review completed" you mentioned), you may want to add the Workbench module to the mix (maybe some of its related modules also?), so that the "unset" of these flags only happens after the "status" of some related content type became something like "approved".
As soon as a business profile no longer has any of such flags set, your business content type can be considered as a "finalized" profile.
Possibly you may want to add the Content Access module to the mix, to implement some additional features that you may want to use.
To implement your "dashboard", you just have to build a few (rather basic) reports using the Views module, with appropriate fields, filters, etc related to the various flags.


If you're not familiar (enough/yet) with Rules, checkout the 32 (!!!) great, and free, video tutorials Learn the Rules framework. Possibly also the similar set of 8 video tutorials about the Flag module.