If you make it through training and qualify it's a 2 year commitment. After that if you took a FT position in feeders then you would have to bid back to package but if you stayed on the Q list you can just tell them to take you off the list and go back to running your route in package (you keep your delivery route as long as you're on the Q list). Whether you wait to get some more seniority is up to you, but I don't see the point. Cover in feeders beats cover in package hands down, in fact most would say that cover in feeders beats having a "good route" in delivery.
We pee in a restroom like normal human beings. All the new tractors come with radios, you can listen to whatever you want.