Thanks seymore for all that information! We're flying with a short stopover of a few hours in Singapore where I'd imagine we'll be in an air conditioned airport throughout.
I'm breast and bottle feeding so I'll probably find myself doing more of both, I'd imagine.
Pram: we've got an uppababy cruz which we use with a Smartmuff to convert it into a flat pram. I was worried about the Smartmuff because he'd be lying on a furry base, but I've bought a big tshirt made of wicking fabric that I am going to put over the base and cut slits for the straps, which should make it cooler. One good thing about it is that you can remove the whole top layer of Smartmuff so the baby isn't enclosed by anything, so it shouldnt get stuffy. And the hood bit of the pram has a sunshield that pulls out of it. I can then do your muslin trick if the whole of his body needs shading.
For most of the time we'll be at my husband's parents house which doesn't have aircon but does have evaporative cooling (although not in the bedroom). I would imagine Z would sleep with just a waffle blanket or some layered muslins as he doesn't like being swaddled.
We're also taking the baby Bjorn, but on a hot day does one have to be careful with them as the baby will be getting your body heat too? We've got the "active" one (or whatever it's called), that has vented fabric.
My previous trips to Melbourne have had very variable weather; one time it was 40 degrees and another time it rained every day and I lived in my 1 pair of leggings under my summer dresses. I guess baby clothes are quite easy to layer aren't they.