Clastling Rule

Could somebody please explain to me why rule #4 of Castling 

(The king and the rook must be on the same rank)

is not superseded by rule #1 

(The king and rook involved in castling must not have previously moved) ?

How could the king and rook NOT be on the same rank if none moved?

Rule #4 seems redundant, I do not know what I am missing.

Please pardon my ignorance. I am a simple engineer designing a cheap chess board which can read the moves automatically. What means "Rh1-g1"? Are you moving the Rook from H1 to G1? How is this not a move?

Please pardon my ignorance, what exactly is clastling? 

To the best of my understanding, if neither the rook nor the king have moved, as clearly stated in Rule #1, they will ALWAYS be on the same rank. What amazing circumstance could be where the rules of logic do not follow? Chess is a logical game, the rules must be also logical. Why write a redundant rule? 

I could make many rules which would all be correct, for example "Black rook must always be on A8 or H8 before castling", but why bother since I covered it in Rule #1?

You are correct. The rule about the same rank is pointless - & it's NOT mentioned in the Official Laws of Chess at all. Don't know why anyone thought it was needed.

Some chess variants, such as chess960 (or Fischerrandom), begin the game with the pieces sitting on non-standard squares. Perhaps the two rules were both included (instead of just Rule #1) in order to cover those variant cases.

Under FIDE rules 3.8 covers king moves including castling. It does indeed mention that it is a King and Rook move "along the players first rank"

If you want to know why that is specified...do a google search for "vertical castling"