VPN beginner here, explanation needed

Hi people

I have always been interested in using VPN but never really paid too much attention into it, until now. I have a number of questions that hopefully you guys will be able to provide the answers for. Lets get straight to it:

1. Does using VPN mean I can use any public wifi (restaurants/cafes/hotels/airports) and be 100% worry-free?
2. How exactly do you use a VPN? Is it: connect to internet, turn on VPN, start browsing? or is it turn on VPN, connect to internet, start browsing?
3. Lets say I decide to use VPN. Is the VPN going to be connected to my device/computer or will it be to the ISP? I ask because I am living with my brother. The question is, if I use a VPN, will it be only for my computer, or will it be connected to the ISP as well, in which case my brother will be able to use it as well?
4. Is it normal to use VPN most of the time, when you connect to the internet?
5. As long as I use VPN, connecting to public wifi and checking my social media accounts, my bank accounts, etc. will be safe, correct?

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That is all. Thank you for reading