Choosing firmware version in CyanogenMod or LineageOS I recently acquired a secondhand Samsung Galaxy GT-I9295, currently installed with Android 4.4.2. I would like to install either CyanogenMod, or Lineage, depending on what is available. I am told that the phone is also referred to as an "S4 Active", 

Before even trying to install an altenative OS, I'm facing the problem of trying to discover the correct firmware version. Unfortunately I have no background knowledge of smartphones (this being the first I've used) and I have no idea what I should be looking for in the published lists of CyanogenMod and LineageOS supported models.

The lists on both the LineageOS site and the CyanogenMod have a vast array of Samsung phones but, amongst them, should I be looking only for "GT-I9295" irrespective of what other terms might be used on the same line, or should I be looking for something that says "S4 Active", even if it does not mention "GT-I9295". And are either of the two identifiers that I've mentioned sufficient to identify the correct firmware for the phone or are there some other identifiers (e.g., something I found called "Baseband version" that is listed in the device settings) that I ought be concerned about?
Galaxy S4 Active is not officially supported by either CyanogenMod (back when it was still in action) or LineageOS. Unofficial versions of CyanogenMod and LineageOS are available on XDA-Developers, all the way up to LOS 14.1 (Android 7.1).

As for the other part of your question, contrary to the other answer, you are urged to find ROMs base on the model number (in your case, GT-i9295), and also your baseband version for optional assistance. The reason is there are a number of variants for a phone of the same name; AT&amp;T has their own variant (SGH-i537), and Korean carriers have another very different variant (SHV-E470S). Each could affect what you can and can't flash. For example, E470S has its own array of ROMs to flash, but since the internal is vastly different (despite they look alike), you can't flash it on your own.

If your baseband version starts with "I9295" then you can be sure that your device is indeed a GT-i9295 and can proceed to attempt to flash anything made for it; otherwise, it's likely that the phone is converted from one of the other variants (by flashing a ROM, or spoofing build.prop, whatever), and you should stop and ask for assistance.