I have Condon and Skelly Antique Ins. Pretty much like the rest of the classic ins co's. I'm limited to 2, 500miles per year, per vehicle.
1- depends on personal visit or phone/interweb. My co. Wanted to know C.I.D., trans, options, what was modified, anti-theft device installed, storage location, type of building, etc.
2-you can go with Agreed Value, but it needs to be with in reason. Must have photos of all angles, inside and out, trunk, under hood, underneath if possible. It helps to have receipts, but best of all to protect youself try to get it appraised. There are many reputable appraisers all over the country. Usually around $300. Well worth it in case of a claim. Old Cars Price Guide is close if stock and description is honest.
3- what you have invested at least, unless you go over the top on time and money. Once again, get an appraisal.