The archival node is necessary for normal indexer operation, so I wouldn’t disable archival mode or shut down the node. The config you mention appears to be for the algod node, so I would leave that as is.
Indexer can be started and pointed to the archival node to catch up. The version of indexer is not important so long as it supports the most recent consensus version, but I would recommend using the most recent version, at this time 2.11.1.