Well... still stars but not with conventional fusion, they happen during much more extreme events such as supernovae explosion

So the most common element is hydrogen, followed by helium and so on. Stars are basically fusion reactors that fuse element up untill iron on the periodic table. The Wikipedia page of " Abundance of the chemical elements " will show you how little of the universe is not hydrogen helium. So by mass I'd say it's quite rare for sure, but compared to things like gold or uranium it's far less rare. Most we can do are estimates since it's really hard to find direct evidence on far away planets.

In Italian it is "minuti primi" and "minuti secondi" and they are shortened in "minuti" e "secondi" so minutes don't have the "first" in the name, i am guessing that in Latin it used to work somewhat similarly and the world followed

You see, we know how atoms work by solving very complicated quantum mechanics equations (in the past by hand!) And we could learn things like the orbital shape and other useful properties.

Now, solving everytime equations is hard and most of the time in chemistry there are a lot of shortcuts to make life easier. The octet rule is one of those, and if you look at the f and d block, or the haufbau filling rules you see that the octet is not so much set in stone!

Also, in the past by looking ad atom emission and absorption spectra we could find out quite accurately the energy of the levels, and it his way we can really see how electrons occupy atomic orbitals !