this is not possible. the time a tx was first received depends on the server.
the correct way to sort transactions is to look at their inputs and outputs.
I think that's OK - in practice, transactions are spread fast enough that it won't differ by more than a few seconds, whereas blocks are often over 30 minutes apart.
no, there is no guarantee that different servers will configure their clock with the same time.
in addition, get_history will be extended, and it should be completely deterministic;
a hash of the history will be used to avoid the server resending the whole history everytime it changes.
I'm not sure if I understand how inputs/outputs can be used to sort transactions... could you expound?
when transactions are in the same block, they are logically ordered; you cannot spend coins before you receive them