A:
That ONYX model does need the Car radio and will connect via FM transmission.
Since you don't have a Radio installed you do have 2 options available. Their is a 'Home' unit that provides an AC adapter, inside antenna, AUX audio cable and mounting base unit. I bought that and have it plugged in the AUX input of my CD player in the house.
The other option is to buy the 'Home Player'. Tis is more expensive as it is complete base unit with internal speakers, antenna and AC adapter.
With the 'Home' unit I bought, I can take the Sirus/XM radio from the house and pop it in the car mount and continue listening. When I return home I remove the ONYX unit from the car and take into the house.
Again you need either the car radio or something that has AUX input and speakers. That might be less expensive then replacing the manufactures radio.