You're quite correct. I'm going to use a 5V regulator, which seems to do the job very well on the shields I've seen, so power shouldn't be a problem. The antenna is going to be an issue if I want to make it a track on the PCB, as I have no idea how to route antennas. Does it only have to be a specific length? KiCAD has tooling to help that. Otherwise, I can just stick an external antenna on it, like most shields have.
5V regulator is not correct, that would be too convenient: the module datasheet says "3.3~4.6V 4.0V nominal". They're designed to be driven directly from a LiPo battery (via short leads with appropriate decoupling, power draw is very spikey). The Arduino shield has a LMZ12002TZ switchmode chip on it.
The routing from the device to the antenna needs to be controlled impedance, ie specified width and distance from ground planes. You'll need to leave a ground plane cutout round the SMA connector. Actually building a PCB track antenna requires specialised software voodoo to get right, especially if you want to retain multi-band capability.
(My experience is with a different module with identical specs; we found that 4.8V caused no obvious problems except that maybe 1 in 10 firmware downloads would irrevocably brick the device).
Oh hmm, thank you for that information, it's very useful. I do run it from a LiPo battery, so hopefully that will work well after I decouple it (with what I'm guessing should be a rather large capacitor).
As for the antenna, the SMA route sounds much easier, so I'll probably do that. As for firmware downloads, I pretty much only need the device to make and receive calls, so I shouldn't need to upgrade the firmware much past the first time.
