1. Unfortunately, at the moment, the PI Integrator can only stream data to Apache Kafka, Azure Event Hubs, and Azure IoT Hub. You can see this from the Live Library documentation. The data that would be streamed would need to be specified in a streaming view and the data that would be sent is specified in a the message.
2. Currently, you can schedule views to update ever minute.
3. Performance-wise, the number of tags you can put in a view depends on the amount of data you are planning to send to your view (depending on the view type). However, you will be limited by the licensed amount of streams that the installed version allows. That is, if you are using a 100,000 stream licensed version, you can at max, have 100,000 tags being polled.
4. The integrator can be configured to send either interpolated or exact values to a view.