[Nyororin]

On the regular roads, yes - they will often enforce the limit. It`s usually 45km/h.
But I would follow the flow of traffic. If everyone is going 60, then go 60.

On the smaller roads, well, I doubt you`ll WANT to go over the limit as some are literally only the width of the car without even enough room to open the doors.

As for the expressway, it`s really anything goes. The posted speed is usually something like 60 - but you will encounter 130+ regularly without any enforcement. However, should you be in an accident over the limit, EVERYTHING will be your responsibility and likely paid out of pocket.

You can easily see the highway fees on Google maps for where you are going. It`s not a flat fee, so changes based on distance.

I don`t know about how the license translation works. Hopefully someone can answer that for you.

Traffic really isn`t as bad as people think. Once outside the city or even in it but not during rush hours, it is pretty clear. The thing with calculations on mapping programs/navigation systems/etc - they calculate based on the posted speed limits. Even when it is normal to go at least 100 on the expressway, it will calculate at 60, etc.