1. Wifi should get connected in the phone, but railway wifi are so poor so, it's not the fault of the phone, (kindly try to connect with some other routers)
2. You can manually turn it off in 'S Secure app'
3. Its not the problem with only this handset. So, there's a device maintenance app kindly optimise your device there and mute those notifications from youtube and whatsapp or from somewhere else which you don't want.
4. It's a shutter Lag but this is not a problem hope so.
5. Ya, this is the problem with Samsung Handset so don't worry it's not yours alone.
6. This should be fixed by an Update
7. Remove your cover while charging or multi taksing and don't use other chargers to charge the device
8. (in railways this is the common problem) Still try to contact your service provider.
9. As i told , Check Device maintenance app
If Your problems are too much , kindly visit Samsung Service Center
