Re: Keel repair
The actual process to repair the glass is simple... I'd recommend overdoing it a bit if possible, the keel isn't a good spot to have a failure.
First off though, you need to work out exactly why it cracked. Cracks at the keel, which is an area of the boat that's not supposed to flex at all, can be indicators of something else wrong. Are your stringers rotten? What's supposed to be supporting the hull at that point?
If you know the damage was caused by an accident or a specific problem that you've corrected, you may be ok.
If it's just randomly started leaking and there are cracks, look for a bigger problem. Where's the water/liquid coming from?
You can grind back the cracked glass and cover it with epoxy and cloth to fix the actual cracks. I'd recommend you use the 12x rule... go as deep grinding as you need to, then go out 12x the sides to give the glass and epoxy enough space to grab on. IE, if you grind out 1/2" of glass and resin to get rid of the crack, then go out 6 inches on all sides and re-glass that area.
I'd use epoxy instead of poly resin, because you're not going to get as good a bond with poly (it's called a secondary bond - you're not able to chemically bond to the old material with new poly). Make sure the area you're repairing is dry before you start.
Erik