0/unconfirmed means that your client has seen the transaction
1/unconfirmed means that your transaction has been included in 1 block, at this point you can be reasonably sure someone has picked up your transaction and it’s now in the chain.
as the number of confirmations increases, so does the confidence in the ‘truth’ of the transaction.
There is no way to cancel a transaction.
It is not possible with the current client to resend a transaction.