I'm planning a trip of under a month from Europe to North America, with flights reserved to and from Vancouver. I'm planning to spend a little time in Vancouver, then cross from Canada to USA by land, probably by train. (I will obtain an ESTA beforehand.) Then, I'm going to drive southwards on the coast, and ultimately fly back to Vancouver, and then back home.
As I want to retain some flexibility about my travel plans, I'm not planning to buy a flight back to Vancouver until I'm in the USA and know which city I'll be departing from.
As I understand, US border officials generally want to make sure that tourists plan to return home. So the question is: might this plan of not buying a return flight from the USA before seeking entry (while having a reserved return flight from Vancouver) present a problem?
Bonus points: Is it OK to have just a credit card, no travellers' cheques or cash when entering the USA? Given that one can get cash from ATMs with a credit card.
Added on edit: this question differs a bit from Entering the USA by land border in that I'm asking about whether my return flight from Vancouver would be sufficient to demonstrate to the US border officials that I don't intend to misuse my tourist status.