Ok.. wrote a quick and dirty preprocessor for you number6..
#var=value

any instance of 'var' will be replaced with 'value' in non '#' prefixed lines, and only after the first '='.

Edit: using your example:

#MUTEON=xxxxxx

#MUTEOFF=yyyyyy

#EMPEGPAUSE=zzzzzz

#EMPEGTUNER=ttttttt

#EMPEGPLAYER=pppppp

#MYREMOTETUNER=mmmmmmm

#MYREMOTEPLAYER=nnnnnnnnn

#ENDOFCOMMAND=ffffffff



MYREMOTETUNER=EMPEGTUNER

MYREMOTEPLAYER=EMPEGPLAYER,dddddd,ENDOFCOMMAND

PAUSE.L=MUTEON

PAUSE.CL=vkgkgkg

would yield:

MYREMOTETUNER=ttttttt

MYREMOTEPLAYER=pppppp,dddddd,ffffffff

PAUSE.L=xxxxxx

PAUSE.CL=vkgkgkg