Automatically delete 1 month old documents(without deleting index) in elastic search

For the 1st question, I don't know. May be ask in #kibana for help.
Check that indices exist:

GET _cat/indices?v 

Will give the list of existing indices.

For the 2nd question, please read the documentation : https://www.elastic.co/guide/en/elasticsearch/client/curator/current/index.html