Coolant change on 2007 D4D Yaris - want to be sure I don't mess up

[sven337]

Hi,
I've consulted earlier threads on coolant change.
My Yaris (NLP90L-CHMGXW) has 190 000km and the coolant was never changed. I noticed it was below the "LOW" level a few days back, although it's still running well I'll obviously need to top up... but if I'm going to buy coolant, I might as well replace the existing one since that is supposedly overdue.

I'm trying to locate the radiator drain petcock, which lots of people say are on the right of the radiator. From the top of the car I can reach with my hand at the center of the radiator a part that feels a lot like the 16400 on this schema of my car http://www.japan-parts.eu/EU/2/162522D.png
Except it's way more to the center than it appears on the drawing. I can touch this part, the shape feels correct, but I don't think I could undo it from the top.

Under the car, there's a plastic part that covers most of the area, but there's a hole through it that shows what I think is the drain hole for the radiator, but I'm not fully sure. I'd like confirmation, please!
Attaching picture of the drain hole. Hoping it's not the AC. It kind of feels like I might be touching the AC condenser not the actual radiator :(

In terms of procedure, am I right to think I can probably do this without lifting the car? It looks like I won't be able to undo (and redo) the petcock from the top, because I can *barely* reach it with my fingers so if I were to go in with pliers I would likely just destroy it. So I'll have to go from under, removing the underside which I think I can do without lifting the car. And then reach the petcock and apply the documented procedure here.

Can anyone confirm that I did locate the right elements and that what I'm thinking of doing sounds fine?
I don't want to empty the gearbox by mistake or anything. :)

(Interestingly it also looks like changing the oil might be done without lifting the car... if so that is pretty cool.)

Also, what coolant should I get? You americans seem to care about 1-actually doing the coolant change (mechanics here seem to say it doesn't matter) 2-using genuine Toyota coolant
Do I need to buy it from Toyota?

Thanks!