SELECT COUNT(*) + COUNT(*)

 - COUNT always returns an int data type value.

 - COUNT(*) returns the number of items in a group. This includes NULL values and duplicates.

What is name of text editor in window to type your SQL queries?

If you want to edit only SQL Queries. Then you can use in-built editor like "Notepad". There is no specific SQL Query editor pre installed in window OS.

There is many SQL Editor's are available now days. But I prefer to use "SQL Server Management Studio (SSMS) Query Editor" to edit quires.