Scaling FG planes down to 1/250 is possible and should hold no real problems for you. If you'll give it a try you'll see that you'll seldomly encounter bits as tiny as on David Hathaway's ships.
Ray has already mentioned tabs and paper... Usually, I sand the trailing edges of the wings thin. Depending on the paper you use, this might require to soak the trailing edges with diluted glue first.
Tools? Some good pairs of tweezers (especially the type where you have to press to open, unfortunately I don't know how those are called in english) come very handy with such small models. An assortment of skewers and dowels of different diameters and a rubber eraser for forming the parts... A ball pen for scoring the leading edges... And always keep your blade really, really sharp!
As for the rigging: Here (->http://www.mtp-studio.de/forum/attachment.php?attachmentid=13070
) is a picture of my 1/250 scale Heinkel He60 (from the CFM Admiral Graf Spee
model).The rigging at the floats and the antenna was done with surgical silk (the finest I could get). A transparent nylon thread would be less noticeable, of course. Just as above, you should do some little experiments to find out if you like it and if it's worth the effort.
Oh, there's one FG special issue left: Don't trust the scale as declared on the model sheets! They are quite often faulty.