There is a specific Forum for EDC.
I think it would be better if you placed this question there: Data Engineering Integration -> Enterprise Data Catalog.
EDC (Enterprise Data Catalog) is a metadata repository and not a data movement tool. So your questions around trying to use EDC to ingest data from Kafka would never be done by EDC.
1) Doesnt make any sense as EDC is not a target and will not stored data from a source system.
2) Yes this already exists. EDC has a kafka connector to extract metadata from the topic level. No Custom connection needed.
3) Great. Once again EDC will not do this. You would need one of Informatica's data movement tools to accomplish this.
Not really sure what is trying to be done but if you could share the actual use case we maybe able to point you to the right tool.
Regarding question 3, the tool you may need is Data Engineering Streaming.
See an excerpt from the user guide:
"Use Informatica Data Engineering Streaming to prepare and process streams of data in real time and uncover insights in time to meet your business needs. Data Engineering Streaming provides pre-built connectors such as Kafka, Amazon Kinesis, HDFS, enterprise messaging systems, and data transformations to enable a code-free method of defining data integration logic"
Hope that helps,