Your top question is like... I have no idea what is security. What is good? Such questions cannot be answered easily. Read https://ssd.eff.org/module/your-secu

Your top question is like... I have no idea what is security. What is good? Such questions cannot be answered easily. Read https://ssd.eff.org/module/your-security-plan https://ssd.eff.org/module/your-security-plan - Trying to protect all your data from everything all the time is impractical and exhausting. - There is no perfect option for security. Not everyone has the same priorities, concerns, or access to resources. Your risk assessment will allow you to plan the right strategy for you, balancing convenience, cost, and privacy. - Some install custom ROM because they don't install 3rd party apps like WhatsApp etc but want to use only OpenSource Email - Some may say - using original factory ROM is bad for privacy as Google snoops a lot but they have some assurance that some random script kiddie cannot take over - Some want security but not privacy (i.e) get a ChromeOS - yes everything is given to Google but Google has one of the best security team in the world.