nole
If the aircraft has been on the 'N' reg then getting it back on is fairly straight forward. You'll have to get a U.S trust set up but there are people who specialise in doing it all for you - have a look at
http://www.southernaircraft.co.uk for more details.
As for the IR. Yes, a lot easier than the JAR route in terms of ground exam preparation - it's a lot more practical based (which is how it should be - let's be honest). Best way to do it is pick a school that can provide you with the I-20 paperwork that will enable an M-1 visa to be issued.
Naples Air Centre in Florida seems to be a firm favourote with a lot of people with a high succes rate. I went to California and used Rainbow Air/Angel City Flyers. You'll probably find recommendations for both on these forums.
What I would advise if you go down this road however is to 'team up' with somebody who has experience of the European IFR environment after you qualify for a few hours at least. There are a lot of procedural differences in terms of airspace, clearances, services available etc between the two environments which you wil probably need explaining, the only way of really learning of which is by experience.