When dealing with old decals, it's a good idea to spray them with some sort of fixative (e.g., Testor's Glosscoat, or Krylon Clear Gloss). That should stop them from splitting - but no guarantees.
I've had some experience with gold leafing. It isn't what it's cracked up to be. When it's applied to tiny parts, at least in my experience, it winds up with a powdery texture that just doesn't cut the mustard. I've tried both the "composition" (i.e., imitation) leaf and, on rare occasions, the real stuff (which is EXPENSIVE). I've just about ruled it out for ship models.
Nowadays there are some really nice gold paints on the market. It's been awhile since I've used any of them in any quantity, but when, in one of my weaker moments quite a few years ago, I built the Heller Soleil Royal, I tested out a bunch of them and concluded that Humbrol made the best one. That was a long time ago. I think the modern versions - including, surprisingly, the Vallejo acrylic metallics - are a good bit better. There's also a product called "Liquid Leaf," which comes in a variety of shades. (Some people apparently think that stuff really is gold leaf. It's not; real gold leaf comes only in sheets - that is, "leaves." "Liquid Leaf" is just a fine-grained metallic paint.)
I personally think old-fashioned Testor's gold - in the little tiny jar - is pretty dang good stuff.
On my model of the frigate Hancock I made the "carvings" out of Milliput epoxy putty. Great stuff, but not exactly easy to work with.
What sailing ship modelers really need are aftermarket parts that are relief etched. All sorts of possibilities there.
Another product I wish the etchers would make: alphabets in various sizes and fonts. Seems like the design work for such a sheet would be child's play on a computer. They could even be inclined, for the name on a ship's bow. Seems like all sorts of modelers would find alphabets useful. And one reasonbly-sized sheet could hold hundreds of letters. (The British company Slaters used to make molded styrene alphabets. I used them for the name on the Hancock's stern. But they seem to be long gone.)
One of these days I'm going to spring the cash for the photo-etching set from Micro-Mark ( http://www.micromark.com/micro-mark-pro-etch-photo-etch-system,8346.html ). Looks like it has enormous potential.