Early into the game you likely do not have high enough stats to work in the shops.
Luckily street performing at the Town Square doesn't require any stats.
Plant Sims are created by overuse of pesticides on crops or fruit trees.
Becoming a Plant Sim takes time, but more trees and crops on a residential lot can help, as it is the amount of pesticide a Sim uses over time that can trigger the transformation.
The family album of the Greenman family implies that Gabe O'Mackey and Jason Greenman went on a hiking trip and discovered this society in the mountains near Riverblossom Hills, where Rose Greenman was discovered.