guys, theres plenty of stuff on here about HAI, so do as much research as you can. Its a very good school - the standards they teach are excellent - and of course they can give out J1 visas... however, there are some negative sides...
Their JAA groundschool is the most expensive in the world - $20k+ - its one of the few areas where you can get something back home for a quarter of the price... Also, whatever kind of timeframe you think you'll be done in - add a bit then double it. I know several people (US citizens - so they had a choice) who went to other schools to finish up because it was taking several months just to get stage checks etc...
As for Dual - if you have the option - its always better to fly dual to build up time - less chance of getting into bad habits and more training to make you a better pilot. If you've got 50 or 60 hours to build - the extra for an instructor to get your FAA IR will be the best money you ever spent. for maybe an extra $1500 in instructor fees you'll get something that will save you tens of thousands of dollars/pouns later on. Get some R22 time - you'll need 50 to teach in one over there. Personally, i'd leave turbine/sling/mountain until later - you'll not be doing that stuff with less that 1000hrs realistically anyway. The key to getting a job is networking, not nessecarily qualifications - so make as many friends as you can.
My advice would be to forget about JAA until you come home - get FAA CPL and CFI as quick as possible and get some hours. once you get your foot in the country that visa clock is ticking... you need to get as much done as possible and get some time in instructing (assuming thats what you want to do..) Things like JAA theoretical study can be done at home after you get home (before if you're qualified, or during if you sign up for distance learning once you've got a private)
Having said that - you guys are in a great position - you're going to have the time of your lives