If you do a Google search you'll find lots of information about refinishing/restoring bows. Here is my suggestion on what to do. I use Loctite 420 in the vertical cracks. It's the only glue I know of that wicks into fine cracks. On white glass the crack may be black with dirt. Clean that the best you can. Then you can fill the crack with Loctite using a syringe. After it dries scrape off the excess and sand the limbs down to the glass. The old yellow finish will be gone and the limbs will be white. At that point you have to determine if you want to just refinish the limbs or repaint them white to hide the filled cracks.
I use auto clearcoat in spray cans - put on a few light coats, wait a day or two, wet sand with 600 grit wet or dry paper and repeat two more times. After the final coat I wet sand with 1500 and 2000 grit paper then use a clearcoat swirl remover as polish. If you want a satin finish you could use rubbing compound instead of the 1500 grit.