Originally Posted by edy4eva

Assuming you're flying EK148/EK406, you will get both boarding passes upon checking in (whether online or at the desk in AMS). Your bags will be tagged through to MEL.
Not sure if you're in F or J, but regardless I strongly suggest, specially if it's the latter, you book a hotel (e.g. le meridien which is a 2 minute ride by car from the kerbside) and spend your night in comfort.
You could also stay in the airport hotel (which is 1 level up from the lounges) if you want maximum convenience.