Installing apps, isn't the same as software updates on the phone. Accept the updates while you are on wifi, or in good service area, and it will help your fun continue to function properly.
If you attached you're phone number for password recovery, you can go to forgot password, and get the code texted to you. Which will allow you to reset the password.
Reset your network settings. Settings > Back-Up and Reset > Reset Network Settings. Go back into your WiFi and re-try the password. If it doesn't work, try the default password on your router.
Those sound like 3rd party app pop-ups. Do you have any cleaner apps, or external weather apps, or news apps downloaded onto your phone? If so go to settings > Apps > [Downloaded App] > Uninstall.