Help with oil viscosity (engine and gearbox) yaris 1.3L, and service manual!

[toyo]

Hi, would really appreciate your help, already searched the web and the forum with no luck.

need to know viscosity recommended for 2nz-fe engine, it's a 1.3L and has around 27,000 Miles on it (44,000 kilometers), compression test showed 175-170-170-165 psi but the oil needs to be changed and spark plugs looked pretty old too.

weather in my country is about 13-26 degrees Celsius.

when is the gearbox oil changed recommended? should I get 100% syntethic 75w90 motul?

and for the engine, found a service manual for a 1.5L and recommended 5w30 to improve fuel economy, I plan to go motul or mobil 1 100% synthethic (wich one? should I go semi-synthetic?)

should I go 5w30, 5w40, 10w30 or 10w40?

couldn't find the service manual online, anyone has it?

how often are the belts changed? and timing chane?

thanks a lot for the replies :P