How to get task details via Rest API?

Issue

• Following REST API is used for fetching the node (task) details:

/rest/runtime/{deploymentId}/history/instance/{procInstId}/node

From the list JaxbNoteInstanceLog that it returns it is possible to get Node Name, Node Type, Node ID and Node Date. If the Node is of type User Task how to fetch the data of who worked on that task and what are the data input and data output for that Task. Similarly how to get input / output data for Service Task?
- Is there any easy way we can retrieve the types of the variables so that i can call below URL only for complex object types to return the value as JSON?

http://localhost:8080/business-central/rest/runtime/{DEPLOYMENT_ID}/process/instance/{PROCESS_INSTANCE_ID}/variable/{VARIABLE_NAME}