Does the OEM radiator cap fit properly on this?

I didn’t have any problems fitting the original cap to this radiator. I installed my radiator 5 years ago and I’ve had zero issues.

How much ATF was lost when changing the radiator?

If you only drain the radiator it was about a gallon and a half. I changed my thermostat as well and it was 2 gallons of the 50/50 long life toyota coolant. Bye the way everything is running great on my truck since I changed my replaced the radiator

Are the large hose connections metal?

Yes they are ..I do maintance regularly. I change my radiators every 150k. Denso is a must.

Takes a month to ship to me?

Amazon is saying 1 month because they do not have it in stock and will not for a month. In case you are in a hurry for it, you can order it from us at BMA and will get it within 1 to 3 days. https://www.amazon.com/Denso-221-3124-Radiator/dp/B0049GEC00/ref=sr_1_1?keywords=221-3124&m=A3TZ17P9C9C3UR&qid=1578422433&s=merchant-items&sr=1-1 Please feel free to call or email us anytime you have any questions or if you need anything else. Thank you BMA Auto Parts 888-262-3911