Hello David, and welcome to our forum
about the short vowels,
we have 3 vowels to represent the letter a
another 3 to represent the letter o
and only two to represent the letter i
Ⲁ is pronounced as in "Far" as you said, that is the correct pronunciation of the letter
some people pronounce it as in "at" because it is easier to pronounce that way
Ⲉ is a very short a, as in Arabic فن or دم or عم or ذم
it is not written in arabic, but replaced with a sign called "fat ha" فتحه
Ⲏ is
usually pronounced long a as in "at" but sometimes it is pronounced long Y
u didn't ask about the o vowels not the i vowels so I will skip them for now
Ⲃ is called Wida, or Bida and can be pronounced as W or B
usually it is pronounced W when followed by another vowel, B otherwise
Ⲏ is pronounced as long a , but there is many words that has Ⲏ pronounced deep Y
a good prove for why Ⲏ is pronounced a is a word like that one
Ⲡⲏⲓ
this means "The House" pronounced "Bay"
if Ⲏ was long Y then I would have pronounced it "Byyi" *does it make sense?*
Ⲧ is called "Daw" and usually pronounced D unless it came at the end of the word, in this case it will be pronounced "T"
Ⲑ this is the letter that is pronounced "T" all of the time
there is not "th" in the Coptic language
notice how all Egyptian says "Catolic" instead of "Catholic"
and "Ortodox" instead of "Orthozox"
Ⲫ as you said b or f
it don't know its rule, in our Coptic books they put a dot under this letter when it is pronounced b
but I am sure there is a rule, I just didn't pay attention to it yet
Ϭ should be always pronounced that way, however we (as a community) are not sure if it was really pronounced gsh or something near it.
we always pronounce it sh
Ⲭ is always "k" (in Coptic words)
Note that, all of what I have wrote above apply ONLY on the words of Coptic Origin
Words of Greek Origin is a bit different
you can watch the following video, might help
but as I told u sometimes they pronounce Ⲁ as in "at",plz ignore that Ⲁ is always as in "Far"
other than that the video is cool, and has very correct pronunciation
http://www.youtube.com/watch?v=OGIa4steqVw