I need to know what the part name is and where exactly to buy these at

I am replacing my. Radiator and I need to buy a transmission line that goes to the radiator I guess but I cant find where to buy one at? Do you know what the part is exactly called and where to buy it at and how much? Also I need to know does it matter what kind of coolant I use to put back in my new radiator once I replace it with the new one can I just buy the dollar general cheaper coolant or does it need to be a certain kind or brand andhow many jugs of it do I need to buy?