Clarification regarding released tests

I know that the first 3 tests in the blue book are “real” sats while the rest were never used for the actual test. Also, while doing some actual real SATs found online, I’ve noticed some differences between the tests. Someone posted that January, June and I think december have officially released tests and these often say question and answer service on the front. They also come with the answers just like the real blue book tests. But eg. the november real tests often lack answers and look like really sketchy scans.

Do you guys still do tests if there’s no answers?
Is there any real difference between the quality/accuracy of the “real” real tests and the real tests in the back of the blue book? Which category do the OC tests fall into?