2013 Prius C - Changed Radio Head Unit & Need Advice

Hi - I changed the radio head unit in my 2013 Prius C from the basic model to the GPS unit. I have a couple of questions, and I will preface by asking for my newbiness to be excused:

- The GPS works great, but needs updated...is this possible?
- I cannot get the Entune app to connect with my radio; are there any links / advice anyone could share on this?
- what is the process to update the Entune firmware?
- USB does not work; any tips on that are appreciated!
- what would be needed to get Sirius XM working with it?
- Last, is it possible to get the car’s information to the corresponding app on this unit, and if so, how?

To be honest, I had to use another Prius’s VIN to register with Entune since my car didn’t come with it. I have searched YouTube and anywhere else I can think of for help with all of this - thanks in advance for any advice!