Old Church Slavonic's crazy orthography

From: Christopher Culver
Message: 33292
Date: 2004-06-25

So I've started learning as much as possible about Old Church Slavonic
from the materials at
http://www.utexas.edu/cola/depts/lrc/eieol/ocsol-0-X.html However, I
am baffled by the inconsistent orthography. Regrettably, I don't think
that Yahoo!Groups will pass on my message with Cyrillic presented in
UTF-8, so I'll do what I can with romanisation.

* Why are there two letters representing the same sound /i/, both the
"backwards-n" still used in Russian Cyrillic, and the dotted "I"
known in our alphabet? In what situation did the writers use one or
the other?

* Why were the several Greek letters xi, psi, omega, and theta
preserved in OCS if the could be replaced by other characters? And
was it common in Byzantine Greek to write xi "backwards" in
comparison to what we see in modern printed Classical Greek?

* What is the representation in IPA of the sound written with the
letter yat?

All in all, OCS is quite interesting and I'm happy to see that it is
helping to explain some of the mysteries that always bugged me when
learning Russian, though OCS has enough new mysteries of its own.

Am I correct in assuming that the hard-sign/yeru at the end of a
masculine noun in the nominative is what remains of PIE -os?

Christopher Culver