Your mate is thinking of a rotary polisher burning through. It's not easy to burn through but if you don't know about pressure and movement then you will most likely burn through edges. A DA polisher reduces that risk as it doesn't produce as much heat in the panel and it doesn't have as much raw cutting power (pad and compound dependant), but it also has the big upside of not leaving swirls or holograms in the paint which will be you biggest thing with black paintwork.
This is a great video for beginners looking into getting started.
https://youtu.be/I7q5E8Kz-CY
You may think that he is sponsored by Bilt Hamber but that's not the case. Their products really are some of the best on the market and some of the cheapest too (I have pretty much all of them).
Washing basics:
https://youtu.be/AUytWaLtOOo
Polishing basics:
https://youtu.be/IrkppP6D6KQ
It costs a big chunk of change to get started and it gets quite addictive after a short time because you keep finding things that you "need". If you don't want to spend out on stuff you might not use again then it's probably worth getting a detailer to do exactly what you want done, then you can maintain the car yourself afterwards.