What other interesting places are there?

Hint 1 of 8:

(1) In the adult bookstore, look in the hall opposite the bathroom for a
smaller room that contains an RPG.

Hint 2 of 8:

Also, one of the shelves opens to reveal some Pipebombs.

Hint 3 of 8:

(2) If you stumble around the dark a bit after you've unlocked the door,
you'll find a hidden stash.