Hey @kind-dawn-17532! Welcome to datahub slack 🙂
1. search indexes a number of features of a dataset- including its name, columns, tags & terms applied to it, description, etc! You can search for a specific column name and all related datasets should appear. Let me know if you are having trouble with this! It may be a bug.
2. All functionality is available whether you use Elasticsearch or Neo4j as your graph backend. The lineage, queries, and stats tab will show as enabled if you have lineage, usage, or data profile data about your dataset. Which sources are you connecting with? Your source's ingestion docs will indicate if and how you can enable usage and dataprofiles. Often, lineage is acquired by integrating with a system that provides edges like airflow, dbt, looker, superset, etc!
3. I would recommend creating a new greenplum source. Ideally you could refactor the code a bit to let some logic be shared betwen the two of them. this way you could contribute your source back to OS! Then, you can make sure the Greenplum data platform is ingested by emitting a Data Platform snapshot. That would contain a url to greenplums icon.