"Is it possible to use serial communication on the native port?"...
Yes,
To use serial, make sure the Tools > USB Type
menu is set to
"Serial", and understand Teensy
only becomes a serial device when it
runs your program built with this setting.
Quoted from here.
(Important that you read through this link, as there are other considerations that are important to note in order to use the serial port/ USB for what you are intending.)
"what bps rate should I use?"
A suggested baud rate for USB connections is 57600, however it may be
useful to go beyond this.
Possible rates include: 300, 600, 1200, 2400, 4800, 9600, 14400,
19200, 28800, 38400, 57600, or 115200. All of these are given in bits
per second.
To open a Serial connection, the function Serial.begin(57600); is
required in the setup function. Serial.print(), Serial.println() and
Serial.write() can all be used to send data from the Teensy to the
computer.
Quoted from here