No. There are many places on the earth where the column is “complete” but this isn’t particularly necessary anyway, because we have ways of conclusively piecing it all together even if no place had every possible layer.
Yes, if by consistent you mean that it all appears to fit into the same pattern of evidence and tell the same story of past history.
This is a common creationist myth. Yes, we CAN and sometimes DO use one to easily date the other as needed, but this is only because these relationships have ALREADY been proven to be so certain and constant that we can safely make such assumptions for the sake of expediency. Dating can always be tested directly, and generally is anyway. It just isn’t particularly pressing because, as I noted, the relationship is very reliable and consistent. Given that the only people who think this is questionable are generally against the entire premise of science and the idea of dating things anyway, it’s not much of a concern.