If there is a schema or column change in the source, how does Infoworks handle it? 

Enable the Schema Synchronization option at the table level by passing an advanced configuration. 
Go to Table>Advanced Configuration and set the below key-value pair. Infoworks would detect that there is a change in the schema on the source system end(newly added columns) and will add the new columns to the hive table. You do not need to truncate, re-crawl and re-ingest the data.