Transmission Fluid - My car is ruined - help

[N9QGS]

Okay I think I have my answer, but I will need you guys to verify's this all applies to a Yaris. Im reading to do this yourself (exchange much of the fluid), drain pain of fluid, and refill. Locate and disconnect the transmission return line, and put clear tubing on it to a drain container. Start the car, and put in drive with emergency brake, and you will get the flow of transmission fluid in the convertor and all that draining out and it says to do this process until you see a change in the color of the liquid, then shut engine off, reconnect transmission return line, top fluid, and road test and recheck level. If this is what you recommend I do vs trying to worry about Toyota comments, if its really this easy, Im doing it this weekend. hahah

Anyone know what tool I made need and how to properly identfy where Im disconnecting this transmission line? and what size clear tubing will fit this best? also will I need to keep filling the transmission up during this process (reason I ask draining pan, is putting about 2 to 3 qts of fresh fluid in, if i'm pumping out 10 to 15 qts of old fluid, im gonna run out somewhere, and i dont know if running out while the car is in drive is a good idea)

thanks.. Ron