Hi.

 Re: ɰ
 /ɰ/ is equivalent to what some write as /w/ and orthographically as . This sound is not phonetically [w] because it does not have lip rounding, so some folks (including me) feel that <ɰ> is a more appropriate symbol.  was useful because it was found on typewriters while <ɰ> had to be written in by hand.  Computers are getting better at displaying this stuff, so I say use the more accurate symbol.
 [ç] is different in that there is audible frication and the constriction is further forward in the mouth. [ç] is an allophone of /h/, but [ɰ] is not.
 Actually, [ɰ] is redundant since it is just a short [ɯ] (like [j] is a short [i] and [w] is a short [u]) — we could just use a non-syllabic diacritic.

 Re: (j)
 (j) is supposed to mean /j/.  It doesnt include /ɰ/ — C+/ɰ/+V is not allowed. In other words, Japanese allows an optional /j/ before a vowel and following an optional consonant onset, i.e. V or /j/+V or C+V or C+/j/+V. -  09:52, 2005 Feb 7 (UTC)