Correct. Broadlink 12 x RM4/RM4c minis (for 12 AC units). I’ve put them inside the indoor units close to the IR receivers. Thus no IR blasters laying around.
Yup. Instantly. And if you take your time to measure wattage used by the AC units you can also differentiate between the AC modes (is cooling/heating or in fan mode).
How it looks in Lovelace you can see here.
I can not answer you this one since I am not living in Austrailia. However, with some basic knowledge about electrical systems (basically only Lin, Lout, Nin and Nout) installation is a breeze.