Ssn and bank account questions (Phoenix)

Hi all nice folks on internations. Quick questions please,

1) it says on ssn website it is best to apply for ssn 10 days after arriving while some say do this right away, which one is it?
2) bank account - must I have ssn to open an account?
3) coming from Australia can I buy a car and drive with Aussie license until I get my ssn>>>drivers license?
4) phone - will Att and Verizon accept customers on plans without credit history?

Thanking you all in advance,
M