I have been planning to use all PowerG devices as they seem to be the most desirable. Is there any reason to consider using S-Line?
PowerG has a much wider range and has FHSS in addition to encryption. If cost is not a consideration then no.
Can the PG9303 be painted?
As long as you are careful to not get the paint inside the housing and do not use metallic paint it should be fine.
Motion Detector - Indoor - Is the PG9984P the best overall PowerG motion detector, or is there another model worth considering? There are ceiling fans in areas where a motion will be going.
As a tool I wouldn’t really put detectors on a tier list. The PG9984P is applicable to most interior purposes and has solid false alarm prevention. The PG9914 is another option.
Here is a link to the manual with instructions on placement. Use the placement instructions to determine if the detector is fit for the purpose and location, in general I would recommend the PG9984P.
It would be fully protected from rain and well protected from dust. Is there any reason I couldn’t use an indoor motion like the PG9974P/PG9984P (both with max operating temp 131F), or should I really use the outdoor PG9994?
There is no gray area here with regard to recommendation. If the area is not an interior temperature controlled location, only use outdoor rated sensors.
A porch open to the outside should use an outdoor rated motion sensor as it will be exposed to outdoor effects.
They asked about possibility of a CO on porch
No, the CO detector is intended for indoor use. Also I think your instinct is correct, as a CO detector would have very limited use on a porch open to the outside where the gas will easily disperse.
There are (2) car entry doors, (2) side doors, and (1) window. They want to put contacts on all of them. The garage will likely get to 110-115F in the summer, possibly warmer at times.
A door/window transmitter is a bit more forgiving and less impacted in a garage install than say a motion detector, but I would still recommend using outdoor rated sensors especially given the location and potential temperature/humidity levels of a garage.
I use an outdoor rated sensor in my own garage.
Are the PG9901 BATT and PG9911 BATT good products? Are they really 110dB as advertised or do they fall short?
They are 110dB rated wireless PowerG sirens. I recommend them as the best wireless option for the IQ Panel 4.
I know the QW9104 IQ Remote is discontinued with IQ Remote PG replacing it, but there are QW9104’s available online. Is there anything more desirable about the IQR over the IQR PG or would it be silly to buy an IQR for a new install like this?
The IQR-PG does not support adding custom photo frame photos yet. A thread on other concerns/bug reports is found below. I would generally recommend going with the IQR-PG instead of the discontinued QW9104. We decided to keep the QW9104 available for now in our store because the IQR-PG is not compatible for users with an IQ Panel 2.
You can set sound volume on the IQR-PG independently aside from alarms.
Lastly (for now), are links available for documents that list of supported RF, Z-wave, and Zigbee devices on the IQ4 as of firmware 4.4.0?
A master list is not generally made for each version release. There have not been major changes that I remember for sensors. Individual devices are called out when support is added in the firmware notes.
Generally for automation devices I recommend checking the ADC list here.
The big change with 4.4.0 is support for PowerG automation devices. See below.