classical Greek (and Latin) vowels

In the past, I have read and have had people tell me different things
when it comes to the vowels in Old/Classical Greek (oh, let's say,
around 2,000+ years ago). I would enjoy a definitive, once-and-for-
all answer from you here. =) And, if there is any variation among
dialects when it comes to the vowels, I would be interested to know
of that as well.
(Notae: Pretend the Greek below is in standard Symbol font. Also, I
haven't learned any versions of the IPA 'net translit. yet, but what
I write shouldn't be terribly confusing.)

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- scenario 1

Greek had 5 vowels, with the pairs distinguished only by number of
morae:

I = [I] (high front lax)
I (w/macron) = [I:]
E = [E] (mid front lax)
H = [E:]
A = [a] (low center)
A (w/macron) = [a:]
O = [A] (low back)
W = [A:] (low back)
U = [u] (high back)
U (w/macron) = [u:]


- scenario 2

Greek had 9 vowels:

I = [I] (high front lax)
I (w/macron) = [i] (high front tense)
E = [E] (mid front lax)
H = [e] (mid front tense)
A = [^] (schwa)
A (w/macron) = [a] (low center)
O = [A] (low back)
W = [o] (mid back)
U = [^] (schwa)
U (w/macron) = [u] (high back)


- scenario 3

Something else. I'm guessing it's s1 or something resembling it,
but, of course, that's just a guess.

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In Latin, are the vowel/letter correspondences as follows? I'm
hoping I have it correct, but I just want to verify in case I happen
to be flat wrong...

I = [I] (high front lax)
I = [i] (high front tense)
E = [E] (mid front lax)
E = [e] (mid front tense)
A = [^] (schwa)
A = [a] (low center)
O = [A] (low back)
O = [o] (mid back)
U = [^] (schwa)
U = [u] (high back)

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While I'm on a roll here, referring back to Old Greek, can someone
explain to me the "iota subscript"? I'm assuming it's occured
because of (a) vowel contraction(s). In speech, is this iota
supposed to be pronounced or ignored?

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Thanks for all your help in the past. It's appreciated!

Lisa