Yes, you can use memory card up to 16GB with this phone.
No. Metro 350 is a 2g mobile phone and hence do not support Jio sim card.
Yes, Samsung Metro 350 does have internet function.
Samsung Metro 350 has quite good battery backup. It comes with 1200 mAh removable battery and on a single charge it can last up to almost almost 4 days.
No. You cannot use WhatsApp in Metro 350.