Dan-
Aren't 'projects fun? ;-)

Those look like pretty bad fractures - I'd think that a good deal of reinforcement would be required inside the boat.
And, the previous 'repairs' don't really help the situation. (Gelcoat over bolt heads?)

Can you access the inside of the hull where the fractures are? If you can't reach it, you can't fix it properly. Is it an H-joint boat? It might be easiest to open it up and re-join it, if you are ambitious.....

Is the boat complete with hatch covers, seat, foot pedals?

The repaired boat is going to be heavier, I'd think - will this be a problem?

As far as the 'how-to' -
I'd use epoxy, not polyester for everything - structural repairs and cosmetic.
Also, paint (LPU), not gelcoat, would be my choice.

I certainly wouldn't do this repair for somebody else - it wouldn't really be cost-effective. As a free boat to add to the 'fleet' or a loaner for easy outings, it could be useful. What do you think?