1) No, I don't think it's nicknamey.
2)
Hallie is not too close to
Hayley, especially if the Hayleys live far away. That's not to say I'd have a Hayley/Hallie sibset, but I think friends & cousins are fine.
3) I prefer
Hallie.
Halle has always looked like to me like it should be prn. "Hail" & is too "
Halle Berry-ish" for me
Something looks "off" in Halley
Hally looks incomplete or misspelled
Halley? Hallee? Halli? Hallea? Halleigh? (I don't like the last 3 I listed, but they're alternate spellings, I guess.)
I like
Hallie Kate, but the Pepsi girl (do you remember her?) is named
Hallie Kate http://www.imdb.com/name/nm0004893/
I like
Hallie Elizabeth if that's your mn. I don't think I'm very good w/ mns, but I'll give it a shot.
Hallie Jade,
Hallie Aurora,
Hallie Meredith