I don't have a smoker, but I love slow-cooked BBQ ribs.
Would it be possible to cook ribs for 8-10 hours or however long I like in my kitchen slow cooker, then pop them onto a charcoal barbecue to brown / char when they're soft enough / cooked?
While you could do this. A better method(Provided you have an enclosed grill) would be to set your grill up for indirect heat and slow cook them on your grill. This is how I do ribs and it works amazingly.
You'll have to do things slightly differently if you have a square or round grill. For a round grill try the following:
If you've got a square grill than you probably cannot do the ring method I've described above, instead you will have to figure out how to do indirect heat a different way. A set of banked coals on each side with the meat in the middle or some lit coals placed in the center of some unlit ones on just one side. You need something that can keep a constant low temperature and burn for 4-6 hours. Experiment and see what works for you.
That absolutely could work. There are many methods to par-cook ribs, and then finish them for service.
The main concern you will have is that slow cookers tend to be very inexact. You don't want your ribs so cooked that they cannot stand up to being handled and moved, so that they fall apart when you try to put them on the grill.
Many folks also advocate simmering ribs before finishing them on the grill, although this is controversial, as flavor could be lost to the simmering liquid. Cooks Illustrated recommends (for baby back ribs) simmering for approximately 20-25 minutes at a bare simmer (to prevent over-cooking the thin end of the rack) until the internal temperature of the ribs comes up to 195 degrees. The also suggest simmering in a brine to help season the ribs.
Another method of par-cooking is to wrap the ribs in aluminum foil, and par-cook them in the oven, then finish cook on the grill.