A - First of all, I'm glad you've decided to incorporate weight training in to your program- the stronger you are everywhere, the better, including the arms.
Sure, you can do bicep curls, and that will make that victorious flexed arm pose that much more impressive. The bicep is the bulky muscle that is traditionally flexed and most obviously displayed when one flexes their arm, particularly noticeable when the hand is facing towards the shoulder to which it is being pulled.
For clarification, here's a pic showing off my bicep ;)
However, when you run, your arms are carried in a bent-at-the-elbow fashion with the forearm tilted so that the hands are actually facing each other with the thumbs on top. When the arm is held in this position, the bend (or flexed state) at the elbow is being most significantly handled by the brachioradialis muscle which is the upper ridge of muscle of the forearm.
So, to target this muscle, I highly recommend you include hammer curls, as shown in the pictures below taken from that great site ExRx.net. You can see an animation of this exercise here.