Question:
does this sound wierd or not make sense?
i depend on you
as my constant capstone
Answer:
It's sort of hard to say since you only gave two lines, but I don't think it would soudn weird. Capstone might be a little awkward to sing or seem out of place, depending on how the rest of your song reads. I suppose you could always replace it with "anchor" or another suitable word to convey your meaning.
Answer:
Yes and yes. Sorry.