2. We can set it to the maximum value, which is 2GB (2147483647) - or if we’re using streamed transfers we can go up to 263 bytes (almost 10,000,000 terabytes). But remember that by setting it to a value larger than necessary we may be opening our service (or client) to attacks.
3. Only if the service is expected to receive messages larger than 65536 bytes. And in this case, we’d be increasing MaxReceivedMessageSize on the endpoints where we expect to receive such big messages.
4. If the messages that our client/servers expect to receive are larger than the default value for MaxReceivedMessageSize, then we need to increase this quota.