Aproctor, in a word, no. Insurance is a personal thing, Adrian Flux is a broker, not an insurance company. You may be lucky enough that the insurers you get quotes from through AF don't make the distinction, but most do.
All have the exact same under coating, but get a 93 uk car and it's had 17 years of crap, get an 93 model imported in 2001 and it's only had 9 years of crap, makes sense doesn't it? I have never said you should not get an import, but many say an import is the be all and end all, but a 5 imported in 1995 is likely to be as bad as a 1995 UK car.
Also if your getting a eunos/miata/mx5 and go for the 1.6 (which is definitley the right decision) There is not much in it to be honest, the 1.8 is a better car, and the 1.6 is a bit "revvier", my advice, try both and most won't care.
Make sure you get one I think post 91 (check mx5nutz) as there is a long nose and short nose crank engine, one has MAJOR woodruff(sp?) key issues and it isn't worth the risk unless it's a cheapie. There are 3 crank sizes, short, big and long, the short is the most prone to it (1989 to mid 1991) and it is due to the key being replaced the wrong way round when the cambelt is changed. If the cambelt has been changed 10k+ miles ago and there are no problems, i would not worry too much. All 5s can be effected, but the early 1.6 are (as you said) most at risk, but it can be fixed.
Yes ok, buy on condition, but if you go JDM you get eleccy windows/aircon and more often than not a few cheeky nice bits! Good point, the nice bits are the key selling point, i've seen £1k cars on AT with Zoom consoles, Key!s steering wheels etc.
Another thing worth mentioning before I forget is that get the owner to take you up a dual carriage way and get him to cruise between 65-75 indicated, chances are you'll find around 69ish that the car will shake lots, most do unless people keep on top of the alignment, if so, don't panic, Wheels in Motion do a full fast road alignment for £90 and it'll out handle a lot of things! On the note of handling, dodgy/mis matched tyres REALLY can affect the little mazdas so worth checking them! The skuttle shake is a design flaw that is made worse with out of balance wheels and certain tyres, good call on the alignment though.