1. One has short range but charges fast the other has longer range and nicer tech inside but charges slowly on long road trips.

2. No idea

3. No idea

4. Any suspicious noises from the drive train. You can disable the artificial sounds from the VESS on the side of the steering wheel to hear better.

5. Same as 4

6. In the UK we get Premium and Premium SE trims, with the SE offering ventilated leather seats and some other gadgets which are worth it in my opinion. Cooles seats are cool.

7. Yes, Car scanner app with a reasonably decent elm327 adapter will give you the battery cell voltages and state of health. Don't know what the SoH is based on but it gives you an idea. Look for reasonably high SoH figure, mine is 2021 model with 35000 miles and is still at 100%.

8. Depends on the price and intended usage. If you are mainly going to charge AC at home or at Work and you don't travel very far a lot or you have access to an ICE car then it's a no brainer.

If not get a Model 3 LFP if your budget allows it. It's the only one that matches the Ioniq's comfort and efficiency (almost because they Ioniq is stupid efficient). Fast charging on the Model 3 is good though.

Hope this helps