Ditto, there is a software update for the EX-2 and that one is English only. Not relevant if you bought the EX-1 - congrats by the way on your investment - but perhaps for other people looking at the EX-2
As for the receiver, the KR-413FH has the best signal strength, processing speed and thus, best response time. I don't know the performance benefits over the other receivers in numbers, so I can't comment on the difference you'll experience.