I usually look at the versions of the firmwares but I’ve failed to do so with the Librem. How can I, for example, determine which version I am using for the WiFi card and mobile broadband card, check whether there is a newer firmware and import it?
I don’t think there is good information yet covering this, particularly not the mobile card.
As you say, information about getting WiFi card firmware version and how to update the firmware is readily found in this forum. Actually getting updated firmware to install may be more difficult!
A wide philosophical debate.
In my opinion, it is generally desirable to run up-to-date software.
However I think with the WiFi card I would wait until the vendor can produce a firmware version that just works. It seems to me at the moment that it is a bit of a juggle to get the firmware version to be compatible with the exact set of WiFi and Bluetooth hardware that you personally use.
Also bear in mind that if the firmware breaks the card, you may now be off the air and hence need to be able to restore the old version - so you should actually download the current version that is in your card before worrying about downloading later versions.
Also, I would recommend only upgrading one card at a time (if and when it becomes possible to do both) because if you managed to get yourself off the air on both cards, it would be even more of a hassle if you had to download anything in order to get back on the air (e.g. network via USB direct to PC or e.g. USB to gigabit ethernet dongle or e.g. sneakernet via uSD card or e.g. sneakernet via external USB drive).
In other words, in my opinion, preparation is key.