Vpn and add-ons

If I get NordVpn and I have the following add-ons or actually. How will add-ons in general effect my security, can they leak my ip-adress. I have firefox and the addons, simple translate, disconnect, privacy badger, Profanity filter, Ublock-origin and facebook container. If I have them turned on, how can they compromise my security. And do I still need add-ons like disconnect if I use a Vpn?

And if you have a Vpn turned on like NordVpn or Expressvpn will it automatically connect on the browser you use for your internet searches.