For the amount of work involved, the price really should be great. You also need to check that other parts like e.g. beams was not damaged in the incident. If you have to rebuild panels, you must make moulds and stuff which adds time and cost to the project.

1: It certainly is possible, but will probably add some weight to the boat. It will take some time.

2: You want to use epoxy for repair work. I would first have sanded the bevels I needed, then set up the parts in the jig. You will probably have to consider removing the deck when gluing the parts together.

3: If you work clean and smart, I dont think you will notice the difference in weight between the hulls. If you are a top notch catsailor amongst the best at the worlds you would probably notice.. That is my guess

4: If you work clean and smart, you should be able to get a nice finish by yourself.

If the price was right, I would jump into it. But if you are unfamiliar with composites and multihulls, I would be careful and try to find someone with experience to help out.

Pictures btw. would be nice, to assess the damage and the repair work neccesary. You can get some really good opinions from the guys with lots of boat-fixing-projects experiences on this forum.