I dug up a bit and I guess I can answer some of my own questions (hopefully this is helpful for someone else). I googled the CSC string and got a link for the Sam mobile site. That's how I found out that my phone has a Portuguese firmware. The Sam mobile site says that for this particular firmware there is no update yet. On a different forum (one from France) the general recommendation was to not change to a different firmware, one from a different country/carrier, so I guess that in my case it's probably best to wait.
From my understanding 4.1.2 does not exactly revolutionize this phone (yes, the split screen is nice but not vital), so I'm not exactly dying to get it. If the firmware becomes available on Sam mobile and after several days it's still not available OTA or via Kies, then I will consider using Odin to flash 4.1.2.