oil type and oil pump

[kthnos]

vitara 1998 1.6L/16v (G16B), 5spd, 5dr.
first things first, i know oil type is widely debated anyway. so here are my questions:

1.oil type. i live in crete,greece. winter is about +5C on cold days and summer is about +35C on hot days. so is 5w-30 a candicate? i have seen the suzuki chart per FSM. i currently run 10w-30 (FSM guide), but was hoping to go to 5w-30 for a little more engine efficiency but without compromising protection and lubrication.

2.oil pump. do we even replace this? can`t find anything in the FSM. if yes, how often? my car has like 200k miles on it already.

3.oil pressure. i know a gauge is the best approach, but how about replacing stock oil pressure sender with a higher psi switch? the idea here is to blink the oil lamp (on the dash cluster) BEFORE the catastrophical 3psi stock switch rating. any feedback on this?

thanks,
kostis