Xiaobaitu: Please Help___2nd FP questions

firstly, thank you very much for what you have done for us!

i still have something unclear althought i read there were discussions about fp code and nc.

here are our case.

vsc
07/04 (i140=niw,i-485)

03/05 (1st fp, code=3)

05/05 i-140 approved

06/05 ted additional evidence (medical examination and employment letter)

09/05 called service center for address change and got a letter mentioned the processing of my case was delayed due to awaiting the results of security checks (my wife got similar inforamtion)

10/05 my son's 1st fp (code=1, he was close to 14 yrs old when my 1st fp)

6/06 lud without text message change

7/06 called the center and was told that i would receive a letter about the inquiry(i have not received yet)

yesturday 2nd fp notice(code=1, re-taken fp)

following are my questions.

1) what does the difference in fp code(my 1st fp code=3 whereas my 2nd fp code=1; my 1st code=3 whereas my son's 1st code=1) mean?

2) the nc of my case seems not clear because i got 2nd fp even my pd is earlier those approved niw cases at vsc, does it?

many thanks again.