About the Cracks: (stolen from 4/99 "Sail", with some opinion thrown in)
*Use a Dremel Tool or the tip of a can opener to dig a small channel along the suface of each crack.
*The bottom of the channel should just reach through the gelcoat to the laminate.
*Feather the edges with 100 grit sandpaper.
*Brush the crack and surrounds clean.
*Wet out the surface of the crack and surounding area with a coat of unthickened epoxy resin and hardener.
*Thicken this mixture up by adding high density filler (to a peanut butter consistency)
*Using a stick or plastic spreader, trowel it flush to the surrounding surface removing the excess epoxy. Let dry overnight.
*100 grit, then a wet-sand of 220. If your repair is lower than the surroundng surface, do it again to level it up.
*Once smooth, wipe down with water and a Scotchbrite of similar pad. (this removes amine blush (byproduct of curing process). Let dry.
*Apply 2-3 coats of unthickened epoxy w/ hardender to seal the repair. Carry the edge of subsequent coats out just beyond the previous coat.
*After curing the final coat, sand w/ 220 grit.

It's not a difficult repair providing you can MATCH THE GEL COAT and have the time and necessary tools and supplies it takes to sand and compound the repair. You've got to enlarge the cracks, bevel the edges in order to get a repair that looks O.K. Many of the stress cracks are the result of thicker gel coat being sprayed into the corners at the cabin/ deck joint during construction and the stress of the boat being sailed. Cracks where a glass panel changes plane is the result of a laminate that can not handle the flex loads or more reasonably, it is the gel coat that can't handle the stress. Some C&C's seem to have fairly thick gel coat which results in increased cracking as the boat is used. In my experience, it is seldom a problem with the glass but rather too thick a gel coat. If there is a "local" fiberglass repairman, ask for an estimate on the job. It just might be cheaper than your time and supplies might cost. Another issue is...will the crack reappear because the laminate is flexing?