I wouldn't say it's related in any way to the alphabet in use. Take the English 'a' as an example: skate and car produce two different sounds out of the same letter.
Many alphabets do a good job transmitting sounds. Spanish, French or German are easy to read. English is particularly bad at having any correlation between spelling and pronunciation. "Spelling bee" would make little sense in most languages.
Sure, but F and E and completely different letters, even if they are almost identical (except for the little bar at the base of the E that is missing on the F).
A and Å are different letters, and can't be substituted for each other.
There are languages with true alphabets, ie. there is a one-to-one relation with written letters and sounds. A good example is Turkish. Once you learn the sounds of the 29 letters in the alphabet, you can perfectly pronounce all Turkish words.
Alphabets transmit words, much less so sounds.