Walikumasalam
1. Recommended oil in user manual is 0w20 or 5w30 fully synthetic.
2. Recommended plugs by OEM for Mira eS
NGK : SILKR6D10G
Denso: IXUH22
3. Transmission oil for 2012 Mira eS
Toyota CVT-TC. Don't use any other transmission oil.
Fuel consumption depends on a lot of parameters like driving conditions, traffic, how much you push the car etc. Try to drive with a lighter foot and see if it improves. Keep 32psi air pressure in tyres.