Shouldn't the pronounciation be pyeonji?
I heard khanji
Duolingo pronunciation is known to not be very good. When in doubt I suggest looking a word up online on a dictionary or use the robot voice from Google Translate
Is this a letter of the alphabet or a written letter?
The latter. ;)
It is a letter that u write
Yes like writing a letter to someone
We hope that Duolingo will improve the pronunciation! 감사합니다!