1. The highest output they sell is only >150mw. I've heard that most were more than this, but recently nearly all the people I know of who have gotten them say that now they are for the most part within %10 of 150mw. The cost for a 150MW direct from CNI for people in the US is $700 USD (shipping included) You also have to pay with an international wire transfer from your bank account to theirs which costs $35-$45 depending on your bank, and lastly you have to pay the customs duties when it is delivered. In the US I've been told is about $50 USD; So in the end it can cost about $800 USD, but to the UK it could be different and if you go with the UK distributor there won't be any duties.
2. I'm not sure if they will sell to individuals in the UK, they have a distributor in the UK
www.edinst.com and you may have to buy through them.
3. The old style ones were easily modded to higher powers, but I've been searching the forums and newgroups and have not found anyone who has been able to mod the new ones yet. If you find any info, please post it.
In any case, it would be best to wait until the 6 month or is it 12 motnths warranty is up before you go opening it up, since opening it up beyond changing batteries will void the remainder of the warranty.
Jack