I want my survey response to be truly anonymous

Your user name does not appear in the results of a survey that is set to hide user names. However, an administrator with access to the database that stores survey results can match your identity to your response.

I want to create a survey with lots of questions

The actual limit depends upon the combination of answer types specified for your questions. The table below lists the limits by answer type:

*In rows marked with an asterisk (*), the number given is the total for all columns of both of the types in the row combined. For example, you can create 16 Number and 16 Currency columns, or 30 Number columns and 2 Currency columns, but not 32 Number columns and 32 Currency columns.