some places fit a aftermarket foglight onto the rear bumper. Not as neat as a UK model but you can buy the UK part and do it that way.
More underseal is worth while on the JDM's
Don't have to de restrict it, it's your call. It's something you would have to sort unless some of the importers offer it as a service. Cost of a delimiter is around £175 plus fitting.
Can't answer the warranties bit, some JDM owners will be able to
Don't know of any issues with tiptronic
Silver cars haven't had their top coat of paint so still in the primer That's the reason why there is more of them as they are cheaper