Where are some other groovy places?

Hint 1 of 6:

(1) Check the compartment at the rooftop where you start for a much-needed
Devastator.

Hint 2 of 6:

(2) Explore the pools in the area, too.

Hint 3 of 6:

(3) Check behind the Exotica poster for a Shrinker.

Hint 4 of 6:

(4) Also look behind the chalkboard with the bloody handprint for something,