fred - you misunderstood my (possibly unclear) comments on the UK CAA.
A JAA licence, issued by the UK CAA, is just the same as a JAA licence issued by another member state - however, the revalidation and renewal rules followed by the UK CAA are different to some other member states.
An examiner with the UK authorities may sign a renewal for any period up to five years after the particular rating expired. It's all done, there and then, at the end of the successful flight test, at the airport, no charge to the CAA.
Some other member states demand that if the rating has expired by even one day, then all the paperwork must be returned to the authorities (of whatever country) to be re-issued by the authority themselves.
Various member states say that a revalidation (rating still current) can be signed directly by the examiner, others say it may only be signed by an examiner from their own state (but is still valid if signed by a "foreign" JAA examiner).
Some member states demand a certain amount of recency experience (which may mean flying with an instructor) before renewing an expired rating - some don't.
Some member states will allow you to do the initial I/R in the USA, some will allow single engine I/R to multi engine I/R as an "add on" in the USA (the UK CAA will not [yet]).
Each state has their own interpretation - and I always advise every foreign (non UK CAA) licence holder to get written word from the relative member state authorities, or web site, before going to the expense of any flying.
It all comes down to interpretation and, possibly, each individuals personal experience.
Had a case last year - Swedish (?) girl, JAA rating expired three or four years prior. Went on an assessment ride with an instructor, given a 100% approval and submitted directly for renewal flight test.
Done in same day. Perfect. Paperwork submitted to national authority, by fax, for rating re-issue. Application rejected - as they demand she should have had a minimum amount of training prior to test, she couldn't possibly be that good after so long a break.
Pointed out that she hand flies approaches three or four times a day, six days a week, doing her day job as an instructor and training captain on a regional jet.
Rating issued by return.
In short - you may renew or revalidate any JAA member state rating in an N registered aircraft in the USA - but the paperwork will vary depending on the state in question.
I don't quite follow your second question. If it's expired by one day, or 200 years, then it's a renewal. Again, procedures will vary depending upon which member state you are talking about.
Send me some specific dates and issuing authority information (by PM if you wish) and I'll try to sort you out.
Remember, all, that the MEP and/or instrument revalidation/renewal flight may count as the dual flight required to maintain the validity of your SEP rating, too (even if it's in a twin).