Revalidation are normally not a problem to do in other JAA member states. But the UK-CAA seems to work in mysterious ways sometimes so you better check with them to be sure.
I am myself a IS/JAA-FE and routinely do LPC rides on other nationality´s and at least Scandinavian authorities as well as Irish CAA accept that.
If you want to get H-300 proficiency check in Iceland I´ll be happy to help out but it´s probably not going to be much cheaper than in UK.
i) My type-ratings are valid for only one year, is that normal for helicopter type-ratings? I believe that fixed-wing are valid for two years, why the difference?
The difference! My guess is because helicopters are more complex! I believe that F/W have to revaildate IR every year.