Where is pt-table-checksum finding this hostname?
Your Question 1

Hostname is from the output of SHOW PROCESSLIST. From that output it tries to detect the slaves. If this is not the right outcome for you, then you can define the dsns table with the list of hosts and use --recursion-method=dsn

Part two of your question will need more information, but you may be able to help yourself using PTDEBUG=1 pt-table-checksum &lt;params&gt;

You are welcome to update your original question with the output from the debug if you would like help with understanding the output. 

Disclosure: I work for Percona