I can just picture what’s going on in their heads:  
Sweetie Bot is trying to figure out what’s different with her friends while continuing through the facsimile of life that she exists in. Apple Blank has determined that she just doesn’t care, mostly because vamponies probably don’t age, and are therefore unlikely to develop cutie marks, while robots are the same with the not aging part, while the inorganic nature likely prevents the development of a cutie mark, though she seems to want Scootabat to hurry up. Scootabat is just happy to be able to soar through the sky, though the fact that her friends have no blood to drain makes things much easier in this situation.

Sweetie Belle is in shock and in denial. She can’t believe what’s happened to them, and clank-clops ahead, ignoring everything around them, supercomputed thoughts racing.
 
Apple Bloom’s a practical filly and has accepted what’s gone on. She is keeping herself together both figuratively and literally, but is clearly giving Scoot’s the stink eye.
 
Scootaloo is thrilled at their Nightmare Night transformation, as becoming a vampony has given her magic enough to fly on her own. She hasn’t yet thought about the downsides.