What is CP1 in SQL_Latin1_General_CP1_CI_AI? I was wondering what the "CP1" means in the collation "SQL_Latin1_General_CP1_CI_AI".

This should be the codepage, but doesn't exist a codepage 1 (for ex. I know it exists a CP850, but never heard about a CP1).
CP1 denotes code page 1252 as described in the SQL Server Books Online.  You can also use the query below to identify the collation code page.

SELECT name, COLLATIONPROPERTY(name, 'CodePage') AS CodePage
FROM fn_helpcollations()
ORDER BY name;