Re: your last sentence - This has nothing to do with being an import car or not, the same thing can happen on locally delivered toyotas as well if all those problems existed on the car and dealer can't fixed it. Any 2nd hand cars regardless japanese, euro, aussie holden/ford, import, aust delivered have potential to inherit all the problems you mentioned above depending on your luck, it is not a correct assumption to assume that buying import is such a hassle.
The main issue here is: Do you have in writing that the sale is SUBJECT to dealer being able to fix that problem prior to delivery of vehicle?
This is usually very common where condition of sale is usually 'subject to finance approval' - however when the car has problems often people
overlooked to have it in writing that problems such and such will be fixed by dealer, and if it's relying only on dealer's words then you've got
no legal ground. If you have it in writing, then you are eligible to get a refund since it was not your fault (not because you changed mind), but because the dealer are unable to deliver the car with problems fixed as promised in writing.