I haven't done any in-depth reading about the rigging of French galleys, but I assume the process of setting and furling sails on board such a vessel was pretty much the same as everywhere else - though I wouldn't be suprised if those enormous lateen sails had a few unusual lines or fittings associated with them. (I seem to recall that there are sheaves built into the mastheads to take the halyards, for instance. But my memory may be wrong about that.)
The basic process of furling a sail is pretty simple. The lines holding it down (the sheets and tacks) are slacked off, and the lines used to furl it are hauled in. In the case of a lateen sail, those include primarily the brails and martnets (if any). That operation has the effect of spilling the wind from the sail and turnint it into a loose, sloppy bundle. The gaskets are then used to turn it into a neat, tidy bundle against the lower side of the yard.
In the case of a square-rigged sail, the bundle usually works out to be slightly smaller in diameter than the yard. (One of the most common mistakes among inexperienced modelers is to make the bundles of furled sails too fat.) Those huge lateen sails on a Reale might have been exceptions. If you do some digging in books on late-seventeenth-century warships you may be able to find some good contemporary pictures of galleys with their sails furled. In any case, if you want to rig such a model accurately you need a good set of plans, including a rigging diagram. I believe there's a set of plans for a Reale among the series published by the Musee de la Marine, though they're pretty expensive. Otherwise, the ones in the Landstrom book are pretty good and, I think, reliable. That book has been around for a long time, but my inclination in such cases is to accept what Landstrom says unless there's a good reason to do otherwise.
In a seventeenth-century square-rigged vessel the topsails were handled a little differently than the others. Rather than being lashed into a bundle that was spread along the length of the yard, the center portion of the topsail was gathered into a vertical, cylindrical shape hanging down from the center of the yard, with the clews projecting from the bottom. (I suspect that arrangement got started in the sixteenth century, when the topsail yard was half as long as the lower yard. That configuration would make it awkward to furl the sail along the yard, since the foot of the sail would be twice the length of the head.) It's kind of hard to describe verbally, but almost any contemporary illustration will make it clear. That method of furling topsails seems to have been in use, at least occasionally, for most of the eighteenth century; contemporary pictures from the American Revolution sometimes show topsails furled that way and sometimes don't.
The best guide to topics like this is John Harland's Seamanship in the Age of Sail, an outstanding, beautifully-illustrated reference that contains just about enough information to let the reader sail a ship of practically any period and nationality. Unfortunately it's pretty expensive, but your library may have it; if not, it's certainly available through the Inter-Library Loan service.