Hello!
1. If the driver or front passenger is 170cm you can fit another 170cm person behind him. Its not comfortable but manageable. Just like in any Porsche 911. And the headroom in this car is actually really huge. I'm 180cm and I had to move the driver seat upwards, yet I'm still able to track the car with a motorcycle helmet w/o it hitting the headliner!
2. You can put much stuff into the car as soon as they're in "soft bags". Also the engine lid / deck will get warm but will not melt any fibre or such. I have driven 200km with stuff top of the engine lid w/o issues.
3. You can use the car w/o ever charging it via the charging port but its not recommended, I believe. For the durability of the said HV battery pack. Every time you'll drive in SPORT-mode it will charge batteries, up to like 70%. But then it will use huge amount of fuel (for the 3-cyl engine). I ll say 12-13L/100km when normal is ~8L/100km in 80kph speed.
AND if you dont have enough battery charged the car will not be as fast as with full battery. There's video on the YT where they track the car until batteries are empty and driver feels notable difference in power: