good job with the headlights! and spending Rs. 2k once in maybe 2 years on the radiator coolant is nothing (as long as it's genuine)! the one currently available is pre mixed, so u just have to open the bottle and pour in the radiator. other cheaper options will need to be mixed with water and you'll have to ensure the water is distilled properly. remember, every time your engine gets over heated, it looses quite a few years of its life ! also, we generally hear about choked radiators... is because of stuff that isn't supposed to be in the coolant! so toyota LLC is HIGHLY recommended, even in this price.
have been spraying water in the engine bay on every service. have been avoiding the oil sprays though. even if some servicing guys insist on a little oil to remove the dirt, i make sure that water is sprayed last and oil is removed. at one place have, the guy sprayed water and then dried with pressurized air - this guy had visibly better pressure of air spray as well as water spray. no issues so far. also, engine stays cleaner for longer as no oil was used! have an english manual of a first generation yaris (uk) and has no mention of "no water in engine bay"
2005 onwards model is known to give b/w 15 to 16kms per liter of petrol in city driving.