If this camera is not so far away from each other it's cheaper to get outdoor LTE/wifi and share out the broadband instead of each camera having it's own simcard unless where you are the data sim is dirt cheap!
Something like this Amazon.com: Cudy Unlocked Outdoor 4G LTE Modem Router with SIM...
You will get better response/help if you can post a screenshot of the settings menu or let us know what mobile app does this PTZ uses. There are so many vendors with their own model number so it's difficult to know just by model/firmware.
Which brand/model are you referring to with no IR? I am quite sure my anjvision wide view have IR but so far happy with the results in color so did not test out the IR yet.
Not really, there is customised 12V 15W Led light with a night sensor that can used a POE splitter for the 12VDC which does not consume much power. Currently using it in conjunction with my Solar/battery for ip camera.
ICSEE app? My Anjvision using AC18pro app can stream a wide angle view of both camera stitched together with no issue but sometimes the stitching have some flaws.
55V should still be ok if you used branded CCTV like HIK/Dahua/UNV. Reolink I have no idea because I only do security grade cctv. Reolink is more towards DIY/Hobbylist/SoHo.