is a STAMP enough for new-immigrant??

[asiansweettoe]

I got my immigration visa last month, and I intend to go to US for 3 weeks at the end of this year, when i go to the poe, do I get a stamp on my passport then? If so, by the time I am back, I couldn't get my plastic card yet, can I come back for just staying in US for 3 weeks?and I will ask my husband's relative send the green card to me when they receive it after 3 weeks. I plan to go there permanently from June next year, is that a problem with my green card my relative mailed to me ,when I leave the border, should I show them green card of a stamp is fine, do they leave any mark on the green card? and if i ask ppl to send the card to me, will there be any problem for me to reenter the US?when i go back, they will check green card or a stamp is fine.
Sorry, quite confusing here, but really really appreciate your advise.

[immihelp]

Greencard stamp in passport is as good as real plastic greencard.