So you answered the first question using the book of acts chapter 10 verses 44-48 which basically tells us its possible to receive the holy ghost prior to baptism and since the holy ghost is a sign of salvation or being saved, this goes to say that baptism did not play a role in these disciples salvation. So essentially your argument is right you don't need to be baptized in or to be saved. However there are a few other verses that i should bring to your attention,
Mark 16:16
He that believeth and is baptized shall be saved; but he that believeth not shall be damned.
Ephesians 4:5
One Lord, one faith, one baptism,
Romans 6:3-4
Do you not know that all of us who have been baptized into Christ Jesus were baptized into his death? We were buried therefore with him by baptism into death, in order that, just as Christ was raised from the dead by the glory of the Father, we too might walk in newness of life.
Galatians 3:27
for as many of you as have been baptized into Christ have put on Christ.
And the famous one as you mentioned John 3:5 which tells us we have to be born of the water and of the spirit or we cannot see the kingdom of god and im sure you know there is quite a lot of controversy over this verse and topic. But i think it to be true and ill tell you why with scripture to back it up, so right before Jesus tells Nicodemus you must be born of water and of the spirit Nicodemus asks How can a man be born when he is old? can he enter the second time into his mother's womb, and be born? and Jesus responds with John 3:5 and after that John 3:6-10.
So yes i believe that one can receive the holy spirit prior to baptism which means they are saved as the holy spirit is proof of salvation. But we cant take that for granted as most people dont get the holy spirit as soon as they believe , you do well to believe even the devils believe and tremble so do they have the holy spirit no, it just depends on god if he wants to give it to you before baptism because he knows your going to go get baptized after, or like most of us we get the holy spirit during baptism, or if your in a foreign country god might just give it to you upon belief as he knows your circumstances.