You can think of the radio modules as a signal converter: the sender modulates a 433MHz wave according to the input signal A (amplitude shift keying). The receiver demodulates the signal and provides the signal A at the output.
You can e.g. use UART to handle the actual communication:
connect the arduino's Tx-Signal to the senders input
connect the ...
Yes, there is a way to reset the serial port, by closing it and opening it again. This will also reset the Arduino.
However, I would rather try to understand what's wrong with the communication. You already have a timeout which should apply to all read/write operations.
Print raw strings (make sure you can distinguish strings with and without \n) which you ...
You could try my implementation of VirtualWire to send small data packets between a Pi and an Arduino.
Class to send and receive radio messages compatible with the Virtual
Wire library for Arduinos. This library is commonly used with 313MHz
and 434MHz radio tranceivers.
The 433Utils Library is probably what you're looking for.
The author even provides example arduino sketches. If you want the Arduino to listen the RF-Sniffer is what you need!
There are also more great tutorials online just like this one.
You may want to introduce a powered USB hub between the Pi and the Nano so that the power is coming from the hub rather than the Pi.
As an aside you can also power the Pi itself from the same hub, so the only powercable you need is the one going to the powered hub.