Learn English – What does “snookums” mean

For a man to "keep" a woman, or for a woman to "keep" a man, means that they are having an illicit romantic relationship and the person doing the "keeping" is paying all the bills. Like if a man has a girlfriend and she lives in his house and she doesn't have a job and so he is paying all the expense, than we say that he is "keeping her" and that she is a "kept woman".

Note that this term is not used for a wife, where traditionally the husband was expected to provide a house and pay the bills. It is sometimes used for a husband if he does not have a job but his wife does. But usually in this case it's used as a simile, that is, we don't say, "He is a kept man" but "He is like a kept man." He's not REALLY "kept" because they're married, but they act like he is.

The Bible quote you give, "the Lord bless you and keep you", is archaic language. No one uses the word "keep" today to mean "protect" except when quoting old text. Someone might say "keep you safe" or "keep you from harm" or some other longer phrase.

The astronomical use of "rogue" is somewhat based on the original dictionary meaning:

rogue (n): 2. An elephant or other large wild animal living apart from the herd and having savage or destructive tendencies. 2.1 A person or thing that behaves in an aberrant or unpredictable way, typically with damaging or dangerous effects.

When something is described as "rogue", it normally implies it acts under its own volition, without constraint from some governing body or authority. A "rogue killer" is someone who works alone and who kills in an unpredictable way or for obscure reasons. Trump calls Khashoggi's killers "rogue" to suggest they were not acting under any official orders (presumably from the Saudi royal family).

A "rogue planet" is one that is similarly unattached to any sun or solar system, although obviously without any sinister or dangerous agenda.