1) what are partitions (In qolsys) / do i need them?
Partitions aren’t necessary. they allow you to section off your alarm system so certain users have access to certain areas and specific users can be assigned to each area. It makes it so one an area or areas can be controlled independently.
2) do i wire the siren to one 16 s or both? Ie will one trigger the other via the connection to the panel 2+
The siren would only need to be wired to one takeover. Wiring diagram can be found in the manual Keep in mind the HW 16-s translates wired sensors into wireless. Whatever is wired to one will be transmitted.
Normally Closed for Motions and for the Door Window sensors.
3) what’s the best way to hide the power cable for the panels… I’m assuming pop a hole above the baseboard and run across?
This is dependent on the layout and desired mounting and differ on a case by case basis. However there are several videos on youtube that cover this topic in more detail than I could. Keep in mind signalling for optimal panel placement as well when mounting the panel.