I don't know about the "coincidence" about you dreaming about a bee, and then your sister getting stung... It's either 1) a strange coincidence, 2) God sent you the dream as an important message, and decided to add a sign from waking life to make sure you pay attention to the dream, or 3) since you have a family soul-connection with your sister, your dreams might be affected by events in her own life/soul.

If you think that the answer is number 2, I'll try to give you an interpretation of what the "message" of the dream could be, so you can be thinking about it.  Hope it helps somewhat.

The pool might represent an emotional situation, or your own emotions.  The bee might symbolize being really busy, since we have a common expression in English, "Busy as a bee."  Perhaps you foresee a really busy time of life coming up?  The bee might also be a pun on the English verb, "to be."  Used as a command, "Be!" it means, "exist! Relax!  Your identity is more important than your activity!"

You struggle against this idea, perceiving it to be a threat.

As for the second dream:
Being part of a group much like a sorority-- This is a Greek-style group of women, meaning that your thoughts are caught up in an emotional pattern that is based on a Greek-style philosophy.  There are pages and pages that could be written about Greek thinking, as a historical/sociological/philosophical phenomenon.  I'd rather not delve into that topic now.  Perhaps that is less important, though, than the rest of the dream.  Maybe one convenient way to boil it down is to say that it is a humanistic style of thinking...

Classroom-- you are learning, you are absorbing knowledge, but you are questioning the source of this knowledge, suspecting that it might be devilish.

Old windows-- a powerful symbol.  Windows are openings that should let in light, and truth, not evil spirits.  The fact that they are old suggests that there is something from your past still affecting you, allowing this negative spirit into your "room."  Consider the phrase, "The eyes are the windows of the soul."  Is there something that you have seen in the past that "haunts you" to this day?

I don't think the song you heard in the alarm is coincidence.  It ties into the dream. Rhythm is a repeating pattern.  i think this tells you that your thoughts are stuck in a repeating pattern, haunted by lessons you have learned in the past that are not the lessons that God wanted you to learn.

Does that seem to make some sense?  Let me know what you think.  I could be off.