Craig, here''s my cut at your Q''s:
1. There''s no way you can expect an answer to a rebuild without knowing how much of the internal hardware you plan to replace, how hard it is to find (how old the engine) etc. Talking with a local Volvo mechanic and ballparking a basic rebuild is the best you can do.
2. Count the number of approx lengths of the Gemini
rig wires, add in the insulator (2 add''l connectors) and take that info to your local rigger; he can give you an estimate based on producing the wire + connectors with and without labor. You want to quote local, not from someone like me from some other location.
3. Call a regular vendor (e.g. Cruising Direct, North, etc.), cite the boat (you may need to know the year, as the Gemini design has changed at least once) and they can offer you a standard quote. Pick the vendor based on the quality of sails you plan to ultimately purchase. And/or call the Gemini Builder and ask one of Tony Smith''s folks to offer a ballpark quote; bet the can come as close as the loft for a given build quality.
Jack