What are the pros and cons of buying a car imported from Japan?

There are a number of dealers importing Japanese cars. What are the snags I might not have thought about? Is insurance more expensive? Are spares harder to get hold of?

How can I find out the history of an imported car?

I have a Toyota Hiace which was registered in the UK in 2004 and converted into a campervan. I am told this is an import. How do I find out where it was imported from and what was the history of the van...