When accessing the interface ( cPanel > Metrics > Visitors ), only 1000 entries are displayed.
The cPanel visitor's interface will limit the report to 1000 entries. This information isn't as useful on active sites as manually viewing the log file. This limit was programmed many years ago and is likely due for improvement.
We've opened an internal improvement case for our development team to investigate this further. For reference, the case number is CPANEL-39452. Follow this article to receive an email notification when a solution is published in the product.
None. However, it is possible to download the log with the "Raw Access" interface.