Regarding footropes - the first step in reproducing them convincingly is, as always, to understand how the real thing worked. If you take a look at any of the yards in the Revell kit, you'll notice a row of tiny pegs running along the top of it. Those are simplified representations of the jackstay eyebolts. The jackstay was an iron rod that ran through a series of eyebolts on the top of the yard. It had three purposes. The head of the sail was lashed to it, several rigging lines and blocks were fastened to it, and it served as a handhold for men working on the yard.
The instructions in the first issue of the Revell kit, back in 1959, advised the modeler to make the jackstays from fine piano wire glued (with what kind of adhesive they didn't specify) to the pegs representing the eyebolts. Subsequent versions of the instructions deleted that advice (along with the recommendation to use 36-link brass chain for much of the running rigging).
On the typical yard, the outer end of the footrope was eyespliced into an eyebolt in the iron band near the tip of the yard. The line then passed through eyesplices in the lower ends of a number of "stirrups" - shorter lines hanging down behind the yard, with their upper ends eyespliced to the jackstay. (The lower, lower topsail, and upper topsail yards had three stirrups on each side, the topgallant and fore and main royal yards two, the mizzen royal and main skysail yards one.) The inner end of the footrope was made fast, with another eyesplice, to the jackstay on the other side of the mast. The port and starboard footropes crossed over each other, just ahead of the mast.
The lower yards and the upper topsail yards had additional separate, small footropes called "flemish horses." The outer end of the flemish horse was eyespliced to an eyebolt driven into the very end of the yard; the inner end was eyespliced to the jackstay. The basic layout of all this should be clear from any set of plans.
So far as I'm aware, no sane modeler tries to eyesplice thread of that size on 1/96 scale. Lots of modelers make their footropes out of brass or copper wire, so they can be shaped into the appropriate, gently drooping curves. If you don't want to make the jackstays, a good way to fudge it would be to drill holes in the yards for the wires forming the footropes.
The Longridge book is a grand old classic. He was one of the first of the really serious scale ship modelers; in the 1930s no other book on ship modeling came close to his concern for detail and historical accuracy - to say nothing of his craftsmanship. About the only negative thing that can be said of Longridge's Cutty Sark model is that his model of H.M.S. Victory is even better.
The modern modeler does need to bear a few minor points in mind when working with that book, though. In the first place, it obviously shows its age. It was written before the ship underwent her great restoration of the 1950s, which made some big strides toward returning her to her tea clipper configuration. And many of the techniques Longridge used aren't terribly relevant to today's modeler. He was limited by the tools and materials that were available in the 1920s. He describes, for instance, a silver-soldering technique involving something called a blowpipe, which I've never seen and don't especially want to. And he did simplify some of the details. (Take a look at how he did the cargo winches aft of the fore and main hatches. They're considerably cruder than the Revell versions - which aren't exactly masterpieces of miniaturization.) Harold Underhill was one of the best in the business, and the plans he drew for Longridge's book are excellent. But they don't contain nearly as much detail as the George Campbell set. That's partly because Underhill, of course, was relying on the text of the book to augment what he drew. Campbell was the naval architect in charge of the ship's restoration; he included just about every piece of detail the modeler could possibly use - down to and including the layout of the fixtures in the galley, the clutch mechanism that changed the gear ratios on the cargo winches, and the location of the bookcase in the captain's cabin. Truly amazing plans.
The bottom line is that modelers picking the Cutty Sark are extraordinarily well-served. A mere three sources - the Campbell plans, the Longridge book, and Basil Lubbock's The Log of the Cutty Sark - contain virtually all the information necessary to build a model of any degree of detail the modeler wants.