The admissions packet really is just that nice keepsake admissions letter that comes after the offer. There is nothing in particular really needed from the admission packet. Of course its also used to promote acceptance of the offer.
As far as post-acceptance, all communication you receive is via your vt.edu email address.
Everything you really need to know post-offer is here:
https://vt.edu/admissions/undergraduate/apply/accepting-the-offer.html
And welcome to the Virginia Tech Forum!