By looking around and doing a little research it seems that the throttle body gets the coolant first, then it goes to the oil cooler.

The throttle body gets hot coolant first, then the oil cooler. Both lines to the throttle body can be seen in this picture at the top of the engine where they meet at a 90 degree angle where the throttle body would normally be.

https://i0.wp.com/www.revvolution.co...ment-47225.jpg

What size hoses to get for this?

& What type of hose is required for this (heat rating?)

EDIT: Looks like standard 12.7mm (1/2") heater hose