so I took several villagers around to all 4 plants. What's supposed to happen? On of them went potty and started running around, and even took a boulder over to the cactus...weird!

Check the VV1 guides . You can probably find your answer there.

Good Luck!

That wasn't any help. That's why I'm asking! (g)

The villagers are supposed to study the plants and to become doctors!
take care of what your villagers dislike!

at what point do these things take place? Ive only had a few (2 or 3) and have been plaing for almost 90 total time hours

In studying these plants you can have some doctors and I try to have them, even just trainee, as soon as it's possible!
Before I quit the game, I select 2 of my villagers (generally those who are not in the best health) as doctors, so I'm quieter! (If they are not select as doctor, they don't heal by themselves)