HEYO!!!
So, the controls are actually hidden in the Options menu, and are key customizable.
The pink bar (lust) needs to stay down, and taking anaphrodisiac drug does that. The higher the lust, the hornier you are and the easier your mind breaks.
The orange bar (strength) needs to stay up, and the buffout drug does that. The lower the strength, the harder and eventually impossible resisting attacks become.
The green bar (health) needs to stay up, and taking the morphine and similar drugs does that. The lower the bar, the easier getting knocked out by single attacks is, and then you're just kinda screwed. Literally.
OH!!
And I noticed that the zombies die easier to headshots rather than body shots, and can be tricked into climbing the Shack's second level even if you don't stay on it. I've only played the Shack map so far, and only on the default normal difficulty setting. I've gotten to Zombie wave 6, and there are at least 20 for reference.
Reloading is manual, but can be done at the same time as dash rolling, which is Space.
The default inventory button is R on the computer, which should show a row of slot spaces that hold your original gun, guns you buy, and then the drugs you bought in the right-most slot as a stack. It's a bit weird, but handy to know that drugs will always be in that same spot. To use, click them, then press R again to turn off inventory, then click as if to shoot your gun. Then hurry and re-equip your gun for heaven's sake!