1) Engine oil: Use any good brand in market. usually hx7, Zic, LiquiMoli etc are used. I am using LiquiMoili.
2) Transmission Oil: My info is that 1.3 2NZ has a non cvti transmission gear box. You can use Toyota genuine ATF. but if it has cvti gear box (I dnt think so) then go for Toyota Genuine CVT oil.
3) Spark plugs: Use any good one. I will recommend toyota genuine though people are using other brands like desno. JZ bhai has recommended desno sk20hr11 to docjunaid bhai.
4) I will recommend to use Toyota genuine air filter.
5) Brake oil: Any good brand
6) Tires. The OEM size are: 165/70 R14 and 185/60 R15. So 14' and 15' both will work. You can get any good brand like yokohoma, denlop etc. I like Michelin.
Check the Vitz fan page for more information.
You can also contact murtaza_murti bhai. He is taken as an authority on vitz nd belta on pakwheels
best of luck.