Is it safe to use a Level 3 charger above 100kwh

Yes, certainly. Just keep an eye on the billing rates as larger chargers may cost more when you don't utilise the full capacity. You won't get more than about 77 kW anyway.

There is really nothing you can do that's actually dangerous. EVs are safer than many home appliances.

 

Yes. Much as you can plug a nightlight at 3 W or a toaster at 1500 W into the same outlet, you can trust equipment to pull as much power as it can safely handle and not more.

Note you are typo-ing these units. Watts are a unit of power, that is, they measure the rate at which energy is being loaded into the car (or in general the rate that energy is being moved.) Wh (watt*hour) are a measure of energy. So your total battery capacity is 64 kWh (of energy), which is the amount of energy you'd charge the battery with in 1 hour at 63 kW charge rate (power).

Journalists (like me!) get this wrong all the time so I am hyper-vigilant. But things make more sense in the right units, overall.

Congrats on your new car! I have a 2019 model, it has been great and unless someone hits it, probably will be for many years.

 

Don't travel to Saskatchewan. Lots of broken chargers here. Check plug share app.
Edit. If you have a Tesla it will be fine.