Hi,
Sorry for the delay - ben a bit of a slowdown over the holiday season.
1) Yes, that is correct. It shows as much info as it can (depending on what the user has fill in.
2) You can use standard HTML templating, so you can put a link to the articles page on a profile, but unless there is a URL (in the Articles module that you are using) method of searching for authors on UserID this will not be possible - remember, no other module knows anything about the Smart-Thinker modules and vica-versa.
3) Not without integration/cusomisation - you would need to either write or buy a document-manager module that is aware of the Profile function (or is keyed on UserID). At the end of the day, as in point 2, other modules have no knowledge of the ST modules and therefore cannot just "work" with them - there are some exceptions to this - IF they follow a similar architecture (based on the UserID) then it may be possible to use them together. It depends on the other modules you choose though if you see what I mean.