as Lu said, the estimators will give you more accurate figures than me (you'll need to estimate your income from income support and employment for ftb purposes)

ftba - if you're on income support (youth allowance or parenting) you'll automatically get full rate, approx 160 per fn. if you're not on income and your estimate (combined) is over 45k ish for the full financial year, your entitlement may reduce
ftbb - will be paid depedent on your income esitimate for the full financial year (use the estimator for this one) - it will be anything up to 136ish per fn, depending on your estimated income for the lower income earner (whichever of you this is
parenting payment - if you are currently on youth allowance, your income will be low enough to apply for parenting payment (paid at higher rate than youth allowance). it's just been outlined in another thread the amounts, but it's up to 424 if you have no income, your DP less than 800 per fn. it will vary depending on what you're both earning. if you qualify for this payment, you'll qualify for max ftba
rent assistance. approx 130 (a bit more but i'm rounding from laziness lol) per fn is the max with one child. it will depend on how much rent you're paying (again, the estimator will tell you this)

when you go back to work, if you need to use child care, you will qualify for max rate child care benefit if you're on ppp. if you're both working/studying 15+hours per week, you'll have up to 50 hours subsidised each week. if less than 15 hours, you'll get up to 24 hours subsidised care per week (most long day care places charge a 12 hour day) - this reduces the amount you have to pay to the child care each day/week. if you are both working/studying at least an hour a week, you will qualify for the child care rebate as well (each quarter, you'll receive half of what you've paid in child care fees rebated, to a max of about 7.5k each year)


hope that helps!