Baptism and salvation - 2

Is baptism the seal of the new covenant just as circumcision is the seal of Abrahamic covenant?

Can children be baptized into the new covenant, just as children were circumcized into the Abrahamic covenant?

Why not? Those who use covenants to prove that baptism as required for salvation should allow children to be baptized?

Circumcision was a rite only for the people of God (Jews) just as it is now only for those who are in Christ. So one should be saved before he is baptized.

Did circumcision save Abraham? No. (Romans 4). So can baptism save us now, if a parallel exists?

Children didnt know what their circumcision was for, so does that mean those who are being baptized need not know that it is for "the remission of sins" ?

Some Jews thought that it was their circumcison that saved them (Acts 15:1), do some "Christians" now think that it is their baptism that saved them?

"One last thought: If someone maintains that baptism is necessary for salvation, is he adding a work, his own, to the finished work of Christ? If the answer is yes, then that person would be in terrible risk of not being saved. If the answer is no, then why is baptism maintained as being necessary the same way as the Jews maintained that works were necessary?"

Is baptism required for salvation?