Malayalam virama

[Anthony P Stone]

In connection with the development of an International Standard on Indic
transliteration, there are some points about the Malayalam virama on which
I should like to appeal to list members for help. 

As I understand it, the Malayalam virama (which looks like a free-standing
breve) has the  following special uses in writing Malayalam language, apart
from its 'normal' use of removing the inherent vowel:

it turns the preceding vowel into half-u in the situations (a), (b) -

(a) final in a word, after the vowel 'u', always;   

(b) final in a word, after the inherent 'a'; except as in (c), (d) -

(c) if the word is a single consonant with its inherent vowel + virama,
then the virama has its normal meaning; 

(d) final ya+virama means y + "half-i" (in pronunciation).

(e) medial ya + virama also means y + "half-i", equivalent to the old
cillu-ya [pure consonant form of 'y'].

Questions:

(1) Is there any case where a single consonant with its inherent vowel +
virama means the word formed of that consonant + half-u?

(2) Is the half-u present in any other Dravidian language, where it is not
distinguished in its usual script, but shown when the language is written
in Malayalam script?       If so, which method is used to show half-u?

(3) Are the cases (a) - (e) correct and exhaustive (taking into account
both the old and new  styles of writing)?

Many thanks,   Tony Stone

Dr Anthony P. Stone, Project Leader, ISO/TC46/SC2/WG12 Transliteration of
Indic scripts.  
Email: stone_catend at compuserve.com             Thinking aloud on
transliteration:
   http://ourworld.compuserve.com/homepages/stone_catend/translit.htm