E pawn for black in KID and Sicilian Dragon

I'm looking for insights on the E pawn for black in the Sicilian Dragon and KID.

I've been studying the opening lessons for the Sicilian and KID.

In the lesson on the Sicilian Dragon for Black, the E pawn doesn't move for the first 19 moves.  In the KID, the pawn moves e7-e5 on move 6 in the mainline opening.  The lesson even says, "this appears to loose a pawn for black, but it has been the mainline for decades."

1.  Please explain the different strategies with the E pawn in these two defenses for black.  From my perspective as a beginner/intermediate, they look like similar opening defenses, yet the E pawn gets used very differently.

2.  Also, in the KID lesson, why would black make the e7-e5 move and appear to loose the pawn, and why didn't white take it on move 7.

3.  As a beginner intermediate, should I avoid these two openings--are they for advanced players?

Thanks!

Stephen

Yeah...avoid both of these openings........you can play e5 or d5 against e4 and d5 against d4