Fuel cap and tank venting

Hello All, couple of questions. I just got a new tank and sender for My 73 Duster and they are identical to what I pulled off. Q1 is the filler cap vented or not? I would think it is a sealed cap what with emissions of the period. Q2 the tank has 1 nipple and the sender has the 2, 1 for supply 3/8 and a 5/16. for a vent or return. Can I plumb this with a looped hard line off the tank nipple or ?