Short answer: Data collected - no additional data collection. Other sites on the web will continue to collect whatever they collect.
Short answer regarding effects: No content effects, unless you turned on the preference by hand. If the preference is on, an additional header is sent to those listed websites. If the preference is on, content in websites is modified such that some words (from a list, related to the themes of Mr. Robot) will display upside down briefly.
i missed a detailed explanation: