Features explaination
Wireless car play, is this blue tooth and can we plug a phone in without this? What's the benefit of this option?
Apple Carplay Android Auto is to use maps, google maps, calls, messages, WhatsApp,spotify, music etc of your mobile apps at the head unit's screen. You can watch video below that explains about carplay features
Do I need the radio dongle, what's this?
DAB Radio
DAB stands for Digital Audio Broadcasting. It's a way of listening to the radio using a digital signal sound, rather than analogue radio (FM/AM). DAB is not available in the US. See list below
https://en.m.wikipedia.org/wiki/Countries_using_DAB/DMB
Why would I need the OBD adapter?
OBD2 is a vehicle diagnostic tool that can be connected to the OBD port of the car under the steering wheel. It shows fault codes via an app at the head unit's screen.