Can’t help with a lot of this but you can’t transfer avios to qantas miles, they are not interchangeable
i imagine 27th December is high season but i’ll have a look at the qantas redemption finder when I get a second, however it’s unlikely to reflect availability for avios bookings
who are you proposing to fly DPS-MNL with? QF don’t fly that route unless via sydney
eta: there is availability using QFF points PER-SYD-DPS on the 27th but only flex, no saver availability (and i’m looking at this as a plat so probably seeing more than many are). As an aside, unless you have a pressing need to transit Sydney why not just fly PER-DPS direct?