3) Yes, they are called 1, 10818, 10819
Those are the 3 default databases, postgres, template0 and template1. If there are no other folders then there are no other databases. Now go back to your old data folder, I guess you said it was "C:\PostgreSQL_Data\data". Click on the "base" sub-folder. What folders are under that. Is it just those same 3 sub-folders? If it is, then you must not have been using that as the data folder as you had thought you were. If this is the case, go to the "C:\Program Files\PostgreSQL\8.2\data\base" folder. What sub-folders do you see there?