>>530525001
>the storyline
Super Earth government is basically Super China in the way they view the galactic environment as well as their own citizens, and readily sacrifices and psyops their own people for "the greater good", resulting in every single one of the three enemies of Super Earth to have been directly caused by the actions Super Earth themselves.
The bugs were originally aliens turned into GMO space cattle that went out of control, the bots were overworked second class citizens that unionized, and the Illuminate were just minding their own business until Super Earth decided they wanted to genocide them and steal their technology.
Super Earth lied about the bugs, bots, and squids being cut and dry monsters in order to convince their citizens to hate them, and in doing so managed to mold all three of them into the exact kind of extremists they pretended they were. Super Earth dug their own grave, and their citizens are kept in the dark so well that they don't even know how bad things really are.

>penetration and how to select weapons
This >>530525120
Just keep in mind that every enemy has differently armored parts that require different levels of penetration, and it's a bit of trial and error unless you want to use a wiki.

>personal objectives
Just do whatever it says and you get medals to spend on your warbonds. Easy as that.

>I'm having fun but I also feel lost asf the entire time like a rookie expendable just being told to shoot and don't die and leave the thinking to someone else.
This is unironically in-character for any sort of cadet, and I find that amusing.