1. easy refutation - go to sistine chapel, look up
You're claiming that the ceiling of the Sistine Chapel is better (not just as good, but better) than everything Leonardo and Bellini ever painted. The number of art historians who'd agree with that statement is zero.
2. This is not how people painted with oil until the 19th century.
http://static.squidoo.com/resize/squidoo_images/-1/draft_len...
3. completely unsupported.
Your counterclaim is likewise completely unsupported. But anyone who wants to settle the matter can choose any "how to paint" type book published in the 20th century, and they'll see that was considered the default technique.
4. carving marble is much easier
Carving marble requires more specialized training, but the kind of difficulty I was talking about was how critically viewers judge the result. They are tough on sculpture too, but I think they are as tough on line drawing. The less there is, the more closely it's examined.
5. At the time it was painted in thin, transparent layers that did not allow the kind of reworking
http://en.wikipedia.org/wiki/Pentimento
http://www.escholarship.org/editions/data/13030/d9/ft1d5nb0d...
6. If you want to offer any actual counterargument about Cezanne's drawing, feel free.