A visit to the prototype of what one's modeling is always an excellent idea - if one can afford it. There's nothing quite like seeing for yourself what a great sailing ship looks like. I remember when, as a high school freshman, I saw the Constitution for the first time. No drawing, painting, or model could have made me as conscious of how tall those masts are.
In using a restored ship as a source of information for building a model, though, a couple of things need to be remembered. First, most ships (including this one) go through lots of modifications before they get restored - and those modifications have a way of taking place after the time when the ship became most famous. The preserved carrier Yorktown looks scarcely anything like she did in World War II, and the Constitution looks quite a bit different from how she did during the War of 1812. If you compare the Revell kit to the real ship, you'll find a disconcerting number of differences. There is evidence, for instance, that at various times in her career the Constitution's transom has had three, five, six, and eight windows in it. It currently has three; that configuration probably dates to the 1830s or thereabouts. The Revell kit, which is based on some high-quality research carried out by an excellent scholar, George Campbell, under the auspices of the Smithsonian, has six. The kit attempts to represent her 1814 configuration - and in my opinion does a pretty good job of it. If I were building it I'd probably omit the gunport lids. (The evidence suggests pretty firmly that she had removable shutters, rather than hinged lids, during the War of 1812). Otherwise, I don't know of any major changes I'd make to the kit for the sake of accuracy. (There are plenty that I'd make for the sake of detail and practicality. Those plastic belaying pins and hammock netting stanchions, for instance, would have to go.)
Second, the costs of ship preservation projects are so enormous that the people responsible for them inevitably are forced to make compromises. In her most recent restoration the Constitution's internal hull structure underwent some pretty big - and decidedly non-eighteenth-century - changes. I don't know for sure about paint on the decks, but it wouldn't surprise me. (The deck planking in the shot Mr. Grune was kind enough to post looks remarkably like pressure-treated pine. It may not be, but I certainly wouldn't use that photo as a guide to what her deck planking looked like in 1812.) Her rigging is made of some sort of durable synthetic rope, rather than hemp; I don't know what material those beautiful white sails are made of, but it sure looks modern. The paints are chosen, not because their composition is authentic, but because they hold up well under the rigors of weather and tourists. The list goes on.
The Constitution actually makes fewer compromises with authenticity than many other restored ships. H.M.S. Victory, for instance, has lower masts made of steel pipe, and in order to reduce the strain on her structure they aren't stepped on the keel. Several heavy steel rods are welded to each mast; the rods go through the bottom of the hull on either side of the keel and are embedded in the concrete of the drydock underneath. I believe the spars of the restored Cutty Sark are steel as well. And much of what the visitor sees of the exterior hull of the U.S.S. Constellation (which has suffered horribly under the ministrations of well-meaning "restorers" over the decades) is fiberglass.
We're lucky indeed to have these grand old ships to educate and inspire us. I have the deepest respect for the people who are willing to devote such enormous amounts of time, energy, and expertise to restoring and maintaining them. (When the Constitution was in service, her captain could rely on a maintenance staff of about four hundred people - full-time. Imagine what it would cost to give her that sort of ongoing care today.) But model builders wanting to use them as sources of information need to be careful.
On a couple of other small points - the side of a sailing ship, including the part that projects above the weather deck, is called a bulwark (pronounced BULL-work). The equivalent part of a small boat - the upper part of the side, where the oarlocks are located - is called the gunwale (pronounced GUNNel). "Wale" is a generic term for an unusually heavy belt of timber running the length of the ship; the gunwale got its name because guns originally were mounted on it. I guess it would be technically correct to call the railing forming the top of a ship's bulwark the gunwale, but I'm more accustomed to seeing the term used in the context of small boats.
Current research suggests that the inside surfaces of the Constitution's bulwarks during the War of 1812 were a dull, medium green. The once common practice of painting them, and various pieces of deck furniture, red was fading from fashion by then (though the gun carriages may have been red). The story about the red paint being used to camouflage blood may have some truth to it, but it's now pretty well established that red lead paint was simply a cheap, reasonably durable primer. I've seen references to red paint on the planking of the orlop deck (the lowest deck, just above the hold - invisible on a model); I have no idea whether the U.S. Navy ever adopted that practice. I've also seen dark red lead paint on the steel decks of twentieth-century warships.