Right away, you should know that you'll need to really be on top of the watering for these plants. i've had two of them, and if they dry out, they are gone quick.

i don't really fertilize my plants unless they seem to need it.
they will probably both do fine, if you want to keep them the same size, if you keep them in the same pot they came in. If you put them in slightly larger pots, it might help with the water issue. If you are a cheap skate, i might be able to dig up so old pots here if you want, but they won't be fancy or anything.

i would not "snap" them off. if a plant starts to grow out too much, you should be able to pinch the excess off with your fingernails or cut with a pair of scissors.

you picked out the cutest plants possible! i love english ivy.