How to replace thermostat, water outlet, and temperature sensor

This vehicle is a 2012 Hyundai i10 with 1.1L engine, automatic transmission.
Parts changed:
Water Outlet
Temperature Sensor
Thermostat
Labor hours: 2

Sharing how I replaced the parts through research and basic understanding on how each of the parts work. Special thanks to Hyundai i10 Club of the Philippines.

I noticed that upon after start-up and while engine is running at idle (neutral), while a/c off, radiator does not turn on when it reaches normal heat (approximately 8-10 minutes before fan turns on). It's nearly 20 mins. car still running idle, fan does not turn on. I also noticed that in heavy traffic, a/c blower weakens. Cold air weakens too. Engine humidity is so hot, you can feel the heat within .5m distance.

My own opinion of possible causes:
Busted fan fuse and/or radiator fan
Busted temperature sensor
Busted thermostat
Clogged radiator

Things I did prior to buying parts:
-Checked relays, checked fuses of fan, ac blower using multi meter. All are working.
-Checked radiator fan, working.
-Checked radiator cap, working.
-Checked hoses for any leaks, none.

Attention:
When refilling radiator coolant, always make sure engine is not hot. Do not open radiator cap while engine is hot. After initial refill and after engine is running idle, check water level again. Refill if needed.

Disclaimer:

This is my attempt to DIY.
I am not a mechanic.
Always seek an expert's opinion.