We started with a tandem just like yours, have fun. My vote if you keep the drum is to leave it set up just as it is, on long down hill runs the captain has enought to contend with, let the stoker control the drag brake. If these are the tires that came with the bike when it was new get rid of them now, they have a real sticky rubber that seems to pick up all the junk on the road, we used Conti travel contacts for touring or Schwalbe Stelvios for empty road use. You want to try to avoid flats on a tandem, they can get a little weird when you get a flat tire. One of the reasons I use a drum is to keep the rim heat down when you hit long downhills, one can actually cause flats by having hot rims, go easy with the vee brakes and use the drum in the long downhills.
I am so excited for you, riding as a team is so much fun!